Preparation method of semi-solid battery and its application

Abstract

The present invention provides a method for preparing a semi-solid-state battery and its application. The preparation method comprises the following steps: (1) injecting a polymerizing agent into an assembled battery, aging the battery, and then injecting an electrolyte to obtain a battery that has been injected; (2) allowing the battery that has been injected in step (1) to stand for a gelation reaction, and after the gelation reaction is completed, sequentially performing formation, aging, and volume separation on the battery to obtain the semi-solid-state battery; wherein the polymerizing agent in step (1) includes a solvent with a cationic polymerization function and / or a gelling factor with a cationic polymerization function. The present invention uses an in-situ polymerization method to prepare a semi-solid-state battery. After mixing the polymerizing agent and the liquid electrolyte, the polymerizing agent contains a solvent with a cationic polymerization function and / or a gelling factor with a cationic polymerization function, and a gelation polymerization reaction is initiated in the liquid electrolyte, thereby obtaining a semi-solid-state battery with low impedance, high energy density, and high safety performance.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion batteries, and in particular to a preparation method of a semi-solid-state battery and applications thereof. Background Art

[0002] With the increasing demand for improving the energy density of lithium-ion batteries, traditional lithium-ion batteries have been unable to meet the demand for ultra-high specific energy. The current commercial lithium battery negative electrode materials are mainly modified natural graphite and artificial graphite. Although the preparation technology is quite mature, the theoretical specific capacity of graphite is only 372mAh g -1 , it is difficult to meet the market demand for high energy density lithium-ion batteries. Therefore, based on the demand for high energy density batteries, negative electrode materials with ultra-high specific energy advantages have become a research hotspot. For example: silicon negative electrode, metal alloy negative electrode and metal lithium negative electrode. Taking silicon negative electrode materials as an example, currently, a certain amount of silicon material is mainly used to achieve the purpose of increasing specific capacity. Taking metal lithium negative electrode as an example, its specific capacity is 3860mAh g -1 , the electrochemical potential is -3.04V (vs. standard hydrogen electrode). Batteries made with these negative electrode materials can effectively increase the energy density, even reaching 400Wh kg -1 The above is even higher. The medium and high nickel ternary lithium batteries have high activity. When paired with high specific capacity negative electrode materials, while improving the specific energy density, improving battery safety is also a top priority.

[0003] However, high-energy-density battery materials based on traditional lithium-ion battery systems still present numerous safety risks. These include significant volume expansion and structural changes in the materials themselves, as well as potential cycle life and safety concerns when used with liquid electrolytes. Liquid electrolytes cannot effectively suppress the massive expansion of the silicon anode, nor the structural changes and growth of metal dendrites in the lithium metal anode. These dendrites can potentially pierce the separator, causing internal short circuits within the battery and leading to even greater safety concerns.

[0004] Semi-solid-state batteries can effectively reduce the amount of liquid electrolyte used in the battery, while increasing the energy density of the battery, it also reduces the potential safety hazards caused by the liquid electrolyte. In addition, semi-solid gel electrolytes can effectively inhibit changes in the negative electrode structure and the growth of metal dendrites to a certain extent, while increasing the specific energy density, it can greatly improve the safety performance of the battery.

[0005] CN112133923A discloses a positive electrode material layer suitable for a semi-solid-state battery, a preparation method thereof, a positive electrode sheet, and a semi-solid-state battery. In the positive electrode material layer, polymer fibers serve as a binder to create a network structure, which facilitates the uniform dispersion of the positive electrode active material, solid electrolyte, and conductive agent. The oxide solid electrolyte and polymer solid electrolyte have excellent ion conductivity, thereby improving ionic conductivity. However, modifying the positive electrode material layer only reduces the impedance between the positive electrode material layer and the solid electrolyte, but does not reduce the impedance between the solid electrolyte and the negative electrode.

[0006] CN111430674A discloses an electrode plate and a preparation method thereof, as well as a semi-solid-state battery. The steps include first preparing a core-shell material, then preparing an electrode slurry, coating the electrode slurry on the plate, hot-pressing the coated plate to obtain the electrode plate, and then assembling the plate by lamination or winding. The assembled battery is then injected with liquid, and then subjected to an AG treatment at 45 degrees Celsius for 24 hours, followed by a formation process. After injection, the interface impedance between the plate and the electrode cannot be guaranteed, resulting in a high impedance battery.

[0007] Therefore, how to prepare a low-impedance, high-energy-density semi-solid-state battery is an important research direction in this field. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing a semi-solid-state battery and its application.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] One of the objectives of the present invention is to provide a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0011] (1) injecting a polymerizing agent into an assembled battery, aging the battery, and then injecting an electrolyte to obtain a battery that has been fully injected;

[0012] (2) The battery after the liquid injection in step (1) is allowed to stand for a gelation reaction, and after the gelation reaction is completed, the battery is subjected to formation, aging and capacity separation in sequence to obtain the semi-solid battery.

[0013] Wherein, the polymerizing agent in step (1) includes a solvent with cationic polymerization function and / or a gel factor with cationic polymerization function.

[0014] The present invention uses an in-situ polymerization method to prepare and produce semi-solid batteries. After mixing a polymerizer and a liquid electrolyte, the polymerizer contains a solvent with cationic polymer function or a gel factor with cationic polymerization function, which triggers a gelation polymerization reaction in the liquid electrolyte, thereby obtaining a semi-solid battery with low impedance, high energy density and high safety performance.

[0015] As a preferred technical solution of the present invention, the assembled battery in step (1) includes a positive electrode sheet and a negative electrode sheet.

[0016] Preferably, the raw materials of the positive electrode sheet include a positive electrode sheet main material, a conductive agent and a binder.

[0017] Preferably, the main material of the positive electrode sheet includes LiNi x Co y Mn z O2, NCM111, NCM532, NCM622, NCM712, nickel manganese aluminum, lithium manganese iron phosphate or lithium iron phosphate, or a combination of at least two thereof, wherein a typical but non-limiting example of the combination is: LiNi x Co y Mn z A combination of O2 and NCM111, a combination of NCM111 and NCM532, a combination of NCM532 and NCM622, a combination of NCM622 and NCM712, a combination of NCM712 and nickel-manganese-aluminum, a combination of lithium iron manganese phosphate and NCM622, or a combination of lithium iron phosphate and NCM111, etc. x ≥ 0.8, where the value of x can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8 or 2, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable. y≥0.05, wherein the value of y can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5 or 6, but is not limited to the listed values. Other values ​​not listed in this numerical range are also applicable. z≥0.05, wherein the value of z can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5 or 6, but is not limited to the listed values. Other values ​​not listed in this numerical range are also applicable.

[0018] Preferably, the LiNi x Co y Mn z O2 includes NCM811 or Ni90.

[0019] Preferably, the conductive agent comprises any one of carbon black, acetylene black, multi-walled carbon nanotubes or single-walled carbon nanotubes, or a combination of at least two of them, wherein typical but non-limiting examples of the combination include: a combination of carbon black and acetylene black, a combination of acetylene black and multi-walled carbon nanotubes, a combination of acetylene black and single-walled carbon nanotubes, or a combination of multi-walled carbon nanotubes and single-walled carbon nanotubes.

[0020] Preferably, the binder comprises any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyurethane, styrene-butadiene rubber, polyvinyl alcohol, polyacrylic acid or polyacrylonitrile, wherein typical but non-limiting examples of the combination include: a combination of polyethylene oxide and polyvinylidene fluoride, a combination of polyvinylidene fluoride and sodium carboxymethyl cellulose, a combination of sodium carboxymethyl cellulose and polyurethane, a combination of polyurethane and styrene-butadiene rubber, a combination of styrene-butadiene rubber and polyvinyl alcohol, a combination of polyvinyl alcohol and polyacrylic acid, a combination of polyacrylic acid and styrene-butadiene rubber or a combination of polyacrylonitrile and polyvinylidene fluoride, etc.

[0021] As a preferred technical solution of the present invention, the raw materials of the negative electrode plate include a negative electrode plate main material, a conductive agent and a binder.

[0022] Preferably, the main material of the negative electrode plate includes any one of silicon-doped graphite, lithium metal or metal alloy.

[0023] Preferably, the silicon-doped graphite has a silicon doping amount of 3 to 80%, wherein the silicon doping amount can be 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%, etc., but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable, preferably 5 to 60%, and more preferably 8 to 30%.

[0024] Preferably, the metal alloy includes any one of Ga—Sn, Ge—Se or Sn—Al.

[0025] Preferably, the conductive agent comprises any one of carbon black, acetylene black, multi-walled carbon nanotubes or single-walled carbon nanotubes, or a combination of at least two of them, wherein typical but non-limiting examples of the combination include: a combination of carbon black and acetylene black, a combination of acetylene black and multi-walled carbon nanotubes, a combination of acetylene black and single-walled carbon nanotubes, or a combination of multi-walled carbon nanotubes and single-walled carbon nanotubes.

[0026] Preferably, the binder comprises any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyurethane, styrene-butadiene rubber, polyvinyl alcohol, polyacrylic acid or polyacrylonitrile, wherein typical but non-limiting examples of the combination include: a combination of polyethylene oxide and polyvinylidene fluoride, a combination of polyvinylidene fluoride and sodium carboxymethyl cellulose, a combination of sodium carboxymethyl cellulose and polyurethane, a combination of polyurethane and styrene-butadiene rubber, a combination of styrene-butadiene rubber and polyvinyl alcohol, a combination of polyvinyl alcohol and polyacrylic acid, a combination of polyacrylic acid and styrene-butadiene rubber or a combination of polyacrylonitrile and polyvinylidene fluoride, etc.

[0027] As a preferred technical solution of the present invention, the solvent with cationic polymerization function in step (1) includes 1,3-dioxolane and / or tetrahydrofuran.

[0028] Preferably, the gel factor with cationic polymerization function in step (1) includes any one or a combination of at least two of cyanopolyvinyl alcohol, polyethylene glycol diglycidyl ether or 4,4′-bis(stearamido)diphenyl ether, wherein typical but non-limiting examples of the combination include: a combination of cyanopolyvinyl alcohol and polyethylene glycol diglycidyl ether or a combination of polyethylene glycol diglycidyl ether and 4,4′-bis(stearamido)diphenyl ether, etc.

[0029] As a preferred technical solution of the present invention, the mass ratio of the polymerizing agent and the electrolyte in step (1) is (5-40):100, wherein the mass ratio can be 5:100, 10:100, 15:100, 20:100, 21:100, 22:100, 23:100, 24:100, 25:100, 26:100, 27:100, 28:100, 29:100, 30:100, 35:100 or 40:100, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. Preferably, it is (20-30):100.

[0030] Preferably, the electrolyte in step (1) comprises any one of lithium salt, sodium salt, magnesium salt or aluminum salt, or a combination of at least two thereof, wherein typical but non-limiting examples of the combination include: a combination of lithium salt and sodium salt, a combination of sodium salt and magnesium salt, a combination of magnesium salt and aluminum salt, or a combination of lithium salt and aluminum salt. 15116403291

[0031] In the present invention, the addition of sodium salt, magnesium salt or aluminum salt can initiate polymer polymerization.

[0032] Preferably, the lithium salt includes any one of lithium hexafluorophosphate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium bisoxalatoborate, lithium difluorooxalatoborate or lithium difluorobisoxalatophosphate, or a combination of at least two thereof, wherein typical but non-limiting examples of the combination include: a combination of lithium hexafluorophosphate and lithium bisfluorosulfonyl imide, a combination of lithium bisfluorosulfonyl imide and lithium bistrifluoromethanesulfonyl imide, a combination of lithium bistrifluoromethanesulfonyl imide and lithium trifluoromethanesulfonate, a combination of lithium trifluoromethanesulfonate and lithium tetrafluoroborate, a combination of lithium tetrafluoroborate and lithium bisoxalatoborate, a combination of lithium bisoxalatoborate and lithium difluorooxalatoborate, or a combination of lithium difluorooxalatoborate and lithium difluorobisoxalatophosphate, etc.

[0033] Preferably, the sodium salt comprises NaPF6.

[0034] Preferably, the magnesium salt comprises Mg(PF6)2.

[0035] Preferably, the aluminum salt comprises Al(PF6)3.

[0036] As a preferred technical solution of the present invention, the concentration of the lithium salt is 0.8 to 4 M; wherein the concentration can be 0.8 M, 1.5 M, 2 M, 2.5 M, 3 M, 3.5 M or 4 M, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the concentration of the sodium salt is 0.01 to 0.5 M, wherein the concentration can be 0.01 M, 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.25 M, 0.3 M, 0.35 M, 0.4 M, 0.45 M or 0.5 M, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the concentration of the magnesium salt is 0.01 to 0.5 M, wherein the concentration may be 0.01 M, 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.25 M, 0.3 M, 0.35 M, 0.4 M, 0.45 M or 0.5 M, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the concentration of the aluminum salt is 0.01 to 0.5 M, wherein the concentration can be 0.01 M, 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.25 M, 0.3 M, 0.35 M, 0.4 M, 0.45 M or 0.5 M, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] As a preferred technical solution of the present invention, the aging temperature in step (1) is 20-50°C, wherein the temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 45-48°C;

[0041] Preferably, the aging time in step (1) is 20 to 40 hours, wherein the time can be 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours or 40 hours, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 24 to 36 hours.

[0042] As a preferred technical solution of the present invention, the temperature of the gelation reaction in step (2) is 20-30°C, wherein the temperature can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 23-26°C;

[0043] Preferably, the gelation reaction time in step (2) is 1 to 36 hours, wherein the time can be 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours or 30 hours, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 10 to 20 hours.

[0044] Preferably, the temperature of step (2) is 20-60°C, wherein the temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc., but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable, preferably 40-50°C.

[0045] Preferably, the formation time in step (2) is 10 to 30 hours, wherein the time can be 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours or 30 hours, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 20 to 28 hours.

[0046] Preferably, the aging temperature in step (2) is 20 to 60°C, wherein the temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc., but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable, preferably 40 to 50°C.

[0047] Preferably, the aging time in step (2) is 10 to 20 hours, wherein the time can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours, etc., but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 11 to 13 hours.

[0048] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0049] (1) After injecting a polymerizing agent into the assembled battery, aging the battery at 20 to 50° C. for 20 to 40 hours, and then injecting an electrolyte to obtain a battery having completed electrolyte injection;

[0050] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 20 to 30° C. for 1 to 36 hours. After the gelation reaction is completed, the battery is subjected to a formation reaction at a temperature of 20 to 60° C. for 10 to 30 hours, an aging reaction at a temperature of 20 to 60° C. for 10 to 20 hours, and a capacity separation reaction to obtain the semi-solid-state battery.

[0051] Wherein, the polymerizing agent in step (1) includes a solvent with cationic polymerization function and / or a gel factor with cationic polymerization function.

[0052] A second object of the present invention is to provide an application of the method for preparing a semi-solid-state battery as described in the first object, wherein the preparation method is applied in the field of power batteries.

[0053] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention uses an in-situ polymerization method to produce a semi-solid-state battery. After mixing a polymerizer with a liquid electrolyte, the polymerizer contains a solvent with cationic polymer functionality or a gelling agent with cationic polymerization functionality, which triggers a gelation polymerization reaction in the liquid electrolyte. The resulting semi-solid-state battery has low impedance and high energy density. At room temperature, the battery's impedance can be as low as below 0.22mΩ and its energy density can reach over 250Wh / kg. DETAILED DESCRIPTION

[0056] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0057] Example 1

[0058] This embodiment provides a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0059] (1) After injecting cyanopolyvinyl alcohol into the assembled battery and aging it at 46°C for 30 hours, the electrolyte was injected to obtain a battery with completed injection, and the mass ratio of cyanopolyvinyl alcohol to electrolyte was 20:100;

[0060] The positive electrode sheet of the assembled battery includes: the main material of the positive electrode sheet is NCM811, the binder is polyethylene oxide, and the conductive agent is carbon black, with a mass ratio of 97:1.9:1.1;

[0061] The negative electrode sheet of the assembled battery includes: the main material of the negative electrode sheet is silicon-doped graphite with a silicon content of 30%, the binder is styrene-butadiene rubber, and the conductive agent is carbon black, with a mass ratio of 94.6:2:3.4;

[0062] The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC, and DTD in a mass ratio of 22:28.2:20:12:12:0.5:4.5:0.8.

[0063] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 25° C. for 15 hours. After the gelation reaction is completed, the battery is subjected to a gelation reaction at a temperature of 45° C. for 24 hours, an aging reaction at a temperature of 45° C. for 12 hours, and a capacity separation to obtain a semi-solid-state battery.

[0064] Wherein, the polymerizing agent in step (1) is a gelling factor with cationic polymerization function.

[0065] Example 2

[0066] This embodiment provides a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0067] (1) After injecting polyethylene glycol diglycidyl ether into the assembled battery and aging it at 45°C for 36 hours, the electrolyte was injected to obtain a battery with completed injection, wherein the mass ratio of polyethylene glycol diglycidyl ether to the electrolyte was 15:100;

[0068] The positive electrode sheet of the assembled battery includes: the main material of the positive electrode sheet is Ni90, the binder is polyacrylonitrile, and the conductive agent is carbon black, with a mass ratio of 96:1.8:1.2;

[0069] The negative electrode sheet of the assembled battery includes: the main material of the negative electrode sheet is silicon-doped graphite with a silicon content of 20%, the binder is polyvinylidene fluoride, and the conductive agent is acetylene black, with a mass ratio of 94.9:1.9:3.2;

[0070] The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC, and DTD in a mass ratio of 22:28.2:20:12:12:0.5:4.5:0.8.

[0071] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 23° C. for 20 hours. After the gelation reaction is completed, the battery is subjected to a gelation reaction at a temperature of 40° C. for 28 hours, an aging reaction at a temperature of 40° C. for 13 hours, and a capacity separation to obtain a semi-solid-state battery.

[0072] Wherein, the polymerizing agent in step (1) is a gelling factor with cationic polymerization function.

[0073] Example 3

[0074] This embodiment provides a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0075] (1) After injecting 1,3-dioxolane into the assembled battery and aging it at 48°C for 24 hours, the electrolyte was injected to obtain a battery with a complete injection, wherein the mass ratio of 1,3-dioxolane to electrolyte was 30:100;

[0076] The positive electrode sheet of the assembled battery includes: the main material of the positive electrode sheet is NCM811, the binder is polyethylene oxide, and the conductive agent is carbon black, with a mass ratio of 97:1.9:1.1;

[0077] The negative electrode sheet of the assembled battery includes: the main material of the negative electrode sheet is silicon-doped graphite with a silicon content of 8%, the binder is styrene-butadiene rubber, and the conductive agent is multi-walled carbon nanotubes, with a mass ratio of 97.2:1.8:1.

[0078] The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC, and DTD in a mass ratio of 22:28.2:20:12:12:0.5:4.5:0.8.

[0079] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 26° C. for 10 hours. After the gelation reaction is completed, the battery is subjected to a gelation reaction at a temperature of 50° C. for 20 hours, an aging reaction at a temperature of 50° C. for 11 hours, and a capacity separation to obtain a semi-solid-state battery.

[0080] Wherein, the polymerization agent in step (1) is a solvent with cationic polymerization function.

[0081] Example 4

[0082] This embodiment provides a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0083] (1) After injecting tetrahydrofuran into the assembled battery and aging it at 20°C for 40 hours, the electrolyte was injected to obtain a battery with a complete injection, wherein the mass ratio of tetrahydrofuran to electrolyte was 25:100;

[0084] The positive electrode sheet of the assembled battery includes: the main material of the positive electrode sheet is lithium iron phosphate, the binder is polyethylene oxide, and the conductive agent is carbon black, with a mass ratio of 95.7:2.3:2;

[0085] The negative electrode sheet of the assembled battery includes: the main material of the negative electrode sheet is silicon-doped graphite with a silicon content of 15%, the binder is sodium carboxymethyl cellulose, and the conductive agent is single-walled carbon nanotubes, with a mass ratio of 96.8:2:1.2;

[0086] The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC, and DTD in a mass ratio of 22:28.2:20:12:12:0.5:4.5:0.8.

[0087] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 20° C. for 36 hours. After the gelation reaction is completed, the battery is subjected to a gelation reaction at a temperature of 20° C. for 30 hours, an aging reaction at a temperature of 60° C. for 10 hours, and a capacity separation to obtain a semi-solid-state battery.

[0088] Wherein, the polymerization agent in step (1) is a solvent with cationic polymerization function.

[0089] Example 5

[0090] This embodiment provides a method for preparing a semi-solid-state battery, the method comprising the following steps:

[0091] (1) After injecting 4,4′-bis(stearylamide)diphenyl ether into the assembled battery and aging it at 50°C for 20 hours, the electrolyte was injected to obtain a battery with completed injection, wherein the mass ratio of 4,4′-bis(stearylamide)diphenyl ether to electrolyte was 30:100;

[0092] The positive electrode sheet of the assembled battery includes: the main material of the positive electrode sheet is Ni90, the binder is polyurethane, and the conductive agent is acetylene black, with a mass ratio of 96:1.8:1.2;

[0093] The negative electrode sheet of the assembled battery includes: the main material of the negative electrode sheet is silicon-doped graphite with a silicon content of 15%, the binder is sodium carboxymethyl cellulose, and the conductive agent is acetylene black, with a mass ratio of 95:3.5:1.5.

[0094] The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC, and DTD in a mass ratio of 22:28.2:20:12:12:0.5:4.5:0.8.

[0095] (2) The battery after the injection in step (1) is allowed to stand for a gelation reaction at a temperature of 30°C for 1 hour. After the gelation reaction is completed, the battery is subjected to a formation reaction at a temperature of 60°C for 10 hours, an aging reaction at a temperature of 20°C for 20 hours, and a capacity separation reaction in sequence to obtain a semi-solid-state battery.

[0096] Wherein, the polymerizing agent in step (1) is a gelling factor with cationic polymerization function.

[0097] Example 6

[0098] In this embodiment, except that the mass ratio of cyanopolyvinyl alcohol to electrolyte in step (1) is replaced from 20:100 to 5:100, other conditions are the same as those in Example 1.

[0099] Example 7

[0100] In this embodiment, except that the mass ratio of cyanopolyvinyl alcohol to electrolyte in step (1) is replaced from 20:100 to 40:100, other conditions are the same as those in Example 1.

[0101] Example 8

[0102] In this example, except that the gelation reaction in step (2) was 15 h replaced by 2 h, other conditions were the same as those in Example 1.

[0103] Example 9

[0104] In this example, except that the gelation reaction in step (2) was 15 h replaced by 36 h, other conditions were the same as those in Example 1.

[0105] Example 10

[0106] In this example, except that the gelation reaction at a temperature of 25° C. for 15 h in step (2) was replaced by a gelation reaction at a temperature of 15° C. for 15 h, other conditions were the same as those in Example 1.

[0107] Example 11

[0108] In this example, except that the gelation reaction at a temperature of 25° C. for 15 h in step (2) was replaced by a gelation reaction at a temperature of 35° C. for 15 h, other conditions were the same as those in Example 1.

[0109] Comparative Example 1

[0110] This comparative example is the same as Example 1 except that cyanopolyvinyl alcohol is not added in step (1).

[0111] Comparative Example 2

[0112] In this comparative example, except that the battery after liquid injection is not subjected to gelation treatment in step (2), but is directly subjected to formation, other conditions are the same as those in Example 1.

[0113] The semi-solid batteries prepared in Examples 1-11 and Comparative Examples 1-2 were tested for impedance, energy density, and thermal stability. The test results are shown in Table 1.

[0114] Among them, the test methods for impedance, energy density and thermal runaway are as follows:

[0115] ① Impedance test conditions: Use a 1000Hz internal resistance tester for testing.

[0116] ②Energy density test method:

[0117] a) Constant current constant voltage charging: 0.33C CC 4h to 4.2V, CV to 0.05C;

[0118] b) let it stand for 5 minutes;

[0119] c) Constant current discharge: 0.33C DC to 2.8V;

[0120] d) let it stand for 5 minutes;

[0121] Obtain the discharge energy of a single cell and divide it by the mass of the single cell to obtain the energy density.

[0122] ③ Thermal stability test standard: refer to the steps of SAE J2464, the specific parameters are as follows

[0123] a) Place the battery in an oven, heat it to 120°C at a rate of 5°C / min, and hold for 30 minutes.

[0124] b) heating to 130°C at a rate of 5°C / min and holding for 30 min;

[0125] c) heating to 140°C at a rate of 5°C / min and holding for 30 min;

[0126] d) heating to 150°C at a rate of 5°C / min and holding for 30 min;

[0127] e) heating to 160°C at a rate of 5°C / min and holding for 30 min;

[0128] f) heating to 170°C at a rate of 5°C / min and holding for 30 min;

[0129] g) heating to 180°C at a rate of 5°C / min and holding for 30 min;

[0130] h) heating to 190°C at a rate of 5°C / min and holding for 30 min;

[0131] i) heating to 200°C at a rate of 5°C / min and holding for 30 min;

[0132] When the battery experiences thermal runaway, the test stops and the corresponding temperature at this time is the thermal runaway temperature.

[0133] Table 1

[0134] impedance Energy density Thermal runaway temperature Example 1 0.22mΩ 285Wh / kg 170℃ Example 2 0.21mΩ 270Wh / kg 165℃ Example 3 0.23mΩ 250Wh / kg 170℃ Example 4 0.27mΩ 190Wh / kg 200℃ Example 5 0.24mΩ 265Wh / kg 170℃ Example 6 0.20mΩ 285Wh / kg 140℃ Example 7 0.25mΩ 285Wh / kg 175℃ Example 8 0.22mΩ 285Wh / kg 150℃ Example 9 0.25mΩ 285Wh / kg 175℃ Example 10 0.21mΩ 285Wh / kg 155℃ Example 11 0.25mΩ 285Wh / kg 175℃ Comparative Example 1 0.22mΩ 275Wh / kg 130℃ Comparative Example 2 0.23mΩ 275Wh / kg 130℃

[0135] From the above table we can get:

[0136] The semi-solid-state battery prepared by mixing a solvent with a cationic polymer function or a gel factor with a cationic polymerization function with a liquid electrolyte and initiating a gelation polymerization reaction can achieve lower impedance, higher energy density and significantly improved battery safety.

[0137] By comparing implementation cases 1-5, it can be seen that the semi-solid-state battery of the present invention can achieve good electrochemical performance and safety performance when applied to different positive and negative electrode systems.

[0138] Comparing implementation cases 1, 6, and 7, the concentration of the ionic polymer functional solvent or the cationic polymerization functional gel factor has a great influence on the impedance and thermal stability of the battery. A low concentration will result in an insignificant improvement in thermal stability, and a high concentration will result in a greater increase in impedance. Preferably, the mass ratio of the ionic polymer functional solvent or the cationic polymerization functional gel factor to the electrolyte is (20-30):100.

[0139] Compared with implementation cases 1, 8, and 9, the gelation time will also have a significant impact on the performance of the semi-solid-state battery. A semi-solid-state battery with better comprehensive performance can be obtained when the gelation time is preferably 10-20 hours.

[0140] Compared with implementation cases 1, 10, and 11, the gel temperature is preferably 23-26°C to achieve the comprehensive optimal solution for improving electrochemical performance and safety performance.

[0141] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a semi-solid-state battery, characterized in that: The preparation method comprises the following steps: (1) injecting a polymerizing agent into an assembled battery, aging the battery, and then injecting an electrolyte to obtain a battery that has been fully injected; (2) allowing the battery after the liquid injection in step (1) to stand for a gelation reaction, and after the gelation reaction is completed, sequentially performing formation, aging, and volume separation on the battery to obtain the semi-solid-state battery; Wherein, the polymerizing agent in step (1) includes a gelling factor with cationic polymerization function; The gel factor with cationic polymerization function includes polyethylene glycol diglycidyl ether and / or 4,4'-bis(stearylamide)diphenyl ether; The electrolyte includes a lithium salt; the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; The components of the injected electrolyte are EC, EMC, DEC, LiPF6, LiFSI, LiPO2F2, FEC and DTD; The mass ratio of the polymerizer to the electrolyte is (20-30):

100.

2. The preparation method according to claim 1, characterized in that The assembled battery in step (1) includes a positive electrode sheet and a negative electrode sheet.

3. The preparation method according to claim 2, characterized in that The raw materials of the positive electrode plate include a positive electrode plate main material, a conductive agent and a binder.

4. The preparation method according to claim 3, characterized in that The main material of the positive electrode sheet includes LiNi x Co y Mn z Any one of O2, NCM111, NCM532, NCM622, NCM712, nickel manganese aluminum, lithium manganese iron phosphate or lithium iron phosphate, or a combination of at least two thereof, x≥0.8, y≥0.05, z≥0.

05.

5. The preparation method according to claim 4, characterized in that The LiNi x Co y Mn z O2 includes NCM811 or Ni90.

6. The preparation method according to claim 3, characterized in that The conductive agent includes any one of carbon black, acetylene black, multi-walled carbon nanotubes or single-walled carbon nanotubes, or a combination of at least two of them.

7. The preparation method according to claim 3, characterized in that The binder includes any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyurethane, styrene-butadiene rubber, polyvinyl alcohol, polyacrylic acid or polyacrylonitrile.

8. The preparation method according to claim 2, characterized in that The raw materials of the negative electrode plate include a negative electrode plate main material, a conductive agent and a binder.

9. The preparation method according to claim 8, characterized in that The main material of the negative electrode plate includes any one of silicon-doped graphite, lithium metal or metal alloy.

10. The preparation method according to claim 9, characterized in that The silicon-doped graphite has a silicon content of 3-80%.

11. The preparation method according to claim 10, characterized in that: The silicon-doped graphite has a silicon content of 5-60%.

12. The preparation method according to claim 11, characterized in that The silicon-doped graphite has a silicon content of 8-30%.

13. The preparation method according to claim 9, characterized in that The metal alloy includes any one of Ga—Sn, Ge—Se or Sn—Al.

14. The preparation method according to claim 8, characterized in that The conductive agent includes any one of carbon black, acetylene black, multi-walled carbon nanotubes or single-walled carbon nanotubes, or a combination of at least two of them.

15. The preparation method according to claim 8, characterized in that The binder includes any one or a combination of at least two of polyethylene oxide, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyurethane, styrene-butadiene rubber, polyvinyl alcohol, polyacrylic acid or polyacrylonitrile.

16. The preparation method according to claim 1, characterized in that The concentration of the lithium salt is 0.8-4M; the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

17. The preparation method according to claim 1, characterized in that The aging temperature in step (1) is 20-50°C.

18. The preparation method according to claim 17, characterized in that: The aging temperature in step (1) is 45-48°C.

19. The preparation method according to claim 1, characterized in that The aging time in step (1) is 20 to 40 hours.

20. The preparation method according to claim 19, characterized in that The aging time in step (1) is 24 to 36 hours.

21. The preparation method according to claim 1, characterized in that The temperature of the gelation reaction in step (2) is 20-30°C.

22. The preparation method according to claim 21, characterized in that The temperature of the gelation reaction in step (2) is 23-26°C.

23. The preparation method according to claim 1, characterized in that The gelation reaction time in step (2) is 1 to 36 hours.

24. The preparation method according to claim 23, characterized in that The gelation reaction time in step (2) is 10 to 20 hours.

25. The preparation method according to claim 1, characterized in that The temperature of the formation in step (2) is 20-60°C.

26. The preparation method according to claim 25, characterized in that The temperature of the formation in step (2) is 40-50°C.

27. The preparation method according to claim 1, characterized in that The time for the formation in step (2) is 10 to 30 hours.

28. The preparation method according to claim 27, characterized in that The time for the formation in step (2) is 20 to 28 hours.

29. The preparation method according to claim 1, characterized in that The aging temperature in step (2) is 20-60°C.

30. The preparation method according to claim 29, characterized in that The aging temperature in step (2) is 40-50°C.

31. The preparation method according to claim 1, characterized in that The aging time in step (2) is 10 to 20 hours.

32. The preparation method according to claim 31, characterized in that The aging time in step (2) is 11 to 13 hours.

33. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) After injecting a polymerizing agent into the assembled battery, aging the battery at 20 to 50° C. for 20 to 40 hours, and then injecting an electrolyte to obtain a battery having completed electrolyte injection; (2) placing the battery after the injection in step (1) at rest for a gelation reaction at a temperature of 20 to 30° C. for 1 to 36 hours, and after the gelation reaction is completed, subjecting the battery to a formation reaction at a temperature of 20 to 60° C. for 10 to 30 hours, an aging reaction at a temperature of 20 to 60° C. for 10 to 20 hours, and a capacity separation reaction to obtain the semi-solid-state battery; Wherein, the polymerizing agent in step (1) includes a gelling factor with cationic polymerization function.

34. An application of the method for preparing a semi-solid battery according to any one of claims 1 to 33, characterized in that: The preparation method is applied to the field of lithium ion batteries.