Lithium ion battery based on in-situ polymerization composite solid electrolyte and preparation method of lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and provides a lithium ion battery based on an in-situ polymerization composite solid electrolyte and a preparation method of the lithium ion battery. The preparation method comprises the following steps: mixing a lithium salt, a polymerizable monomer and an inorganic filler to obtain a polymer precursor solution; the method comprises the following steps: coating an inorganic solid electrolyte material, a positive electrode material and / or a negative electrode material with a polymer precursor solution to obtain an inorganic solid electrolyte, a lithium ion battery positive electrode and a lithium ion battery negative electrode; the lithium ion battery negative electrode, the inorganic solid electrolyte and the lithium ion battery positive electrode are sequentially assembled and then subjected to in-situ polymerization, and the lithium ion battery based on the in-situ polymerization composite solid electrolyte is obtained. According to the method, an in-situ polymerization technology is adopted, a polymerizable monomer solution containing a lithium salt and an inorganic filler is introduced between a solid electrolyte and an electrode, and thermal polymerization, photopolymerization or electropolymerization curing is utilized, so that deep infiltration combination between a polymer and an electrode material is realized, and the conductivity and interface compatibility of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery based on in-situ polymerized composite solid electrolyte and its preparation method. Background Technology

[0002] Solid-state lithium-ion batteries have become a research hotspot in the field of electrochemical energy storage due to their high safety and compatibility with lithium metal anodes. However, inorganic solid electrolytes (oxide, sulfide, or halide systems) possess excellent ionic conductivity (oxide systems typically achieve conductivity up to 10⁻⁶ ions / ... -4 -10 -3 While possessing high conductivity (S / cm) and a wide electrochemical window, these electrolytes are limited by their inherent rigidity. This makes them prone to interfacial side reactions due to surface chemical instability when in contact with lithium metal anodes or high-voltage cathodes. Furthermore, poor solid-solid interface contact can lead to increased interfacial impedance. Polymer solid electrolytes (such as polyethylene oxide (PEO) based systems) exhibit advantages like good flexibility, processability, and interfacial compatibility, but their low room-temperature ionic conductivity and limited chemical stability make them unsuitable for high-energy-density battery applications. To balance the performance advantages of both types of electrolytes, current technologies often employ inorganic / polymer composite electrolyte design strategies. However, traditional preparation processes (such as coating, drying, and rolling) are complex and costly. The resulting composite films only achieve macroscopic contact with the electrode surface, lacking interconnected lithium-conducting channels within the electrode, thus limiting ion transport efficiency.

[0003] Therefore, developing an all-solid-state lithium-ion battery with excellent interfacial contact performance, low interfacial impedance, and the ability to construct multiphase interconnected ion-conducting channels has become an urgent need in the field. Summary of the Invention

[0004] In view of this, the present invention provides a lithium-ion battery based on in-situ polymerized composite solid electrolyte and its preparation method, so as to solve the problems of poor interface contact, high interface impedance and limited ion transport efficiency in existing solid batteries.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing a lithium-ion battery based on an in-situ polymerized composite solid electrolyte, comprising the following steps: 1) Lithium salt, polymerizable monomer and inorganic filler are mixed to obtain polymer precursor solution; 2) Coat at least one of the inorganic solid electrolyte material, positive electrode material and negative electrode material with a polymer precursor solution to obtain an inorganic solid electrolyte, a lithium-ion battery positive electrode and a lithium-ion battery negative electrode; 3) The lithium-ion battery anode, inorganic solid electrolyte and lithium-ion battery cathode are assembled in sequence and then in-situ polymerized to obtain a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0006] Preferably, the inorganic filler in step 1) includes Li7La3Zr2O 12 Powder, Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder, Li 10 GeP2S 12 Powder, Li3PS4 powder, Li7P3S 11 One or more of the powder and Li6PS5Cl powder; the particle size of the inorganic filler is 200 nm to 2 μm.

[0007] Preferably, the in-situ polymerization in step 2) includes thermal polymerization, photopolymerization, or electropolymerization; the temperature of thermal polymerization is 50~120℃ and the time is 1~24 h; the ultraviolet wavelength of photopolymerization is 320~400 nm and the time is 10~120 min; the current of electropolymerization is 0~1 C and the time is 0.5~10 h.

[0008] Preferably, the lithium salt in step 1) includes one or more of LiTFSI, LiPF6, and LiFSI; the polymerizable monomer includes one or more of vinyl carbonate (VC), polyethylene glycol diacrylate (PEGDA), 1,3-dioxolane (DOL), ethyl acryloxyethyl ester, methacrylate, and polyepoxy ether; the polyepoxy ether includes one or more of polyethylene glycol diglycidyl ether (PEGDGE), polyethylene oxide (PEO), polypropylene oxide (PPO), polybutane oxide, and poly(ethylene oxide-propylene oxide) block copolymer.

[0009] Preferably, the mass ratio of lithium salt, polymerizable monomer and inorganic filler in step 1) is 5~30:5~30:10~50.

[0010] Preferably, the polymer precursor solution in step 1) further includes an initiator and / or an organic solvent; the initiator includes one or more of azobisisobutyronitrile (AIBN), benzoyl peroxide, 1-hydroxycyclohexylphenyl ketone (Irgacure 184), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure 2959); the organic solvent includes one or more of dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), and propylene carbonate.

[0011] Preferably, the mass ratio of the initiator and organic solvent to the polymerizable monomer in step 1) is 0~2:0~30:5~30.

[0012] Preferably, the inorganic solid electrolyte in step 2) includes Li7La3Zr2O 12 Ceramic flakes (LLZO), Li 1.3 Al 0.3 Ti 1.7 (PO4)3 ceramic sheet (LATP), Li 10 GeP2S 12 Ceramic wafers (LGPS), Li3PS4 ceramic wafers, Li7P3S 11 One or more of ceramic sheets and Li6PS5Cl ceramic sheets.

[0013] Preferably, the positive electrode in step 2) includes one of lithium metal positive electrode, LiFePO4 positive electrode, LiCoO2 positive electrode and NCM811 positive electrode; the negative electrode includes lithium metal negative electrode or silicon-carbon composite negative electrode.

[0014] Preferably, the coating method in step 2) includes drop coating or dipping; the drop volume for drop coating is 0.005~0.50 mL / cm. 2 The soaking time is 0.1 to 5 hours.

[0015] The present invention also provides a lithium-ion battery based on an in-situ polymerized composite solid electrolyte prepared by the above-described method for preparing a lithium-ion battery based on an in-situ polymerized composite solid electrolyte.

[0016] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces a polymerizable monomer solution containing lithium salt and inorganic filler between a solid electrolyte and an electrode, and then polymerizes and solidifies it using methods such as thermal polymerization, photopolymerization, or electropolymerization, forming a dense network of polymer lithium electrolyte interface layer on the surface of the solid electrolyte. This polymer lithium electrolyte interface layer, together with the inorganic solid electrolyte material, constructs a multiphase Li... + Conductive Channels: On the one hand, the inorganic solid electrolyte phase maintains its original high intrinsic ionic conductivity; on the other hand, the polymer electrolyte phase increases overall amorphousness, improves electrode interface adhesion, and can further enhance ion transfer by uniformly dispersing lithium salt in the polymer, thereby significantly reducing interface resistance and improving overall electrolyte conductivity. Furthermore, lithium-ion batteries prepared using the method described in this invention all achieved a conductivity of up to 10 at room temperature. -4 ~10 -3 The high ionic conductivity on the order of S / cm and excellent cycling stability significantly enhance ion transport and compatibility between the inorganic electrolyte and the electrode interface.

[0017] 2. The lithium-ion battery based on in-situ polymerized composite solid electrolyte of the present invention is prepared by in-situ polymerization method, which breaks through the limitation of traditional composite electrolyte membranes that only have surface contact, realizes deep wetting and bonding between polymer and electrode materials, thereby improving the overall conductivity and interface compatibility of the battery. Detailed Implementation

[0018] This invention provides a method for preparing a lithium-ion battery based on an in-situ polymerized composite solid electrolyte, comprising the following steps: 1) Lithium salt, polymerizable monomer and inorganic filler are mixed to obtain polymer precursor solution; 2) Coat at least one of the inorganic solid electrolyte material, positive electrode material and negative electrode material with a polymer precursor solution to obtain an inorganic solid electrolyte, a lithium-ion battery positive electrode and a lithium-ion battery negative electrode; 3) The lithium-ion battery anode, inorganic solid electrolyte and lithium-ion battery cathode are assembled in sequence and then in-situ polymerized to obtain a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0019] In this invention, the inorganic filler in step 1) preferably includes Li7La3Zr2O. 12 Powder, Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder, Li 10 GeP2S 12 Powder, Li3PS4 powder, Li7P3S 11 The inorganic filler is selected from one or more of powder and Li6PS5Cl powder; the particle size of the inorganic filler is 200 nm to 2 μm, preferably 400 nm to 1.8 μm, more preferably 500 nm to 1.5 μm, and more preferably 800 nm to 1 μm; the particle size of the inorganic filler can ensure the dispersibility of the inorganic filler.

[0020] In this invention, the in-situ polymerization in step 2) preferably includes thermal polymerization, photopolymerization, or electropolymerization; the thermal polymerization process is simple and requires low equipment; the photopolymerization temperature is preferably room temperature, which provides mild conditions; the electropolymerization is suitable for generating a polymer layer during the initial charging process; the thermal polymerization temperature is 50~120℃, preferably 55~110℃, more preferably 60~100℃, and even more preferably 65~80℃; the thermal polymerization time is 1~24 h, preferably 2~20 h, more preferably 5~15 h, and even more preferably 10~12 h; the photopolymerization ultraviolet wavelength is 320~400 nm, preferably 325~385 nm, more preferably 330~380 nm, and even more preferably 350~365 nm; the photopolymerization time is 10~120 min, preferably 20~110 min, more preferably 30~100 min, and even more preferably 50~60 min; the electropolymerization current is 0~1 C, preferably 0.1~0.9 C. The temperature C is further preferably 0.2~0.8 C, more preferably 0.3~0.6 C; the electropolymerization time is 0.5~10 h, preferably 1~8 h, further preferably 2~6 h, more preferably 5 h.

[0021] In this invention, the lithium salt in step 1) preferably includes one or more of LiTFSI, LiPF6, and LiFSI; the polymerizable monomer preferably includes one or more of vinyl carbonate, polyethylene glycol diacrylate, 1,3-dioxolane, ethyl acryloxyethyl acetate, methacrylate, and polyepoxy ether; the polyepoxy ether preferably includes one or more of PEGDGE, PEO, PPO, polyepoxybutane, and poly(ethylene oxide-propylene oxide) block copolymer; the number average molecular weight of the macromonomer of the polyepoxy ether is preferably 200-10000, more preferably 400-4000.

[0022] In this invention, the mass ratio of lithium salt, polymerizable monomer and inorganic filler in step 1) is 5~30:5~30:10~50, preferably 8~28:8~28:15~45, more preferably 10~25:10~25:20~40, and even more preferably 15~20:15~20:25~30.

[0023] In this invention, the polymer precursor solution in step 1) preferably further includes an initiator and / or an organic solvent; the initiator preferably includes one or more of azobisisobutyronitrile, benzoyl peroxide, 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone; the organic solvent preferably includes one or more of dimethyl carbonate, ethylene carbonate, diethyl carbonate, and propylene carbonate.

[0024] In this invention, the mass ratio of the initiator and organic solvent to the polymerizable monomer in step 1) is 0~2:0~30:5~30, preferably 0.01~0.18:0.1~25:8~28, more preferably 0.1~0.15:5~20:10~25, and even more preferably 0.12~0.14:10~15:15~20.

[0025] In this invention, the inorganic solid electrolyte in step 2) preferably includes Li7La3Zr2O. 12 Ceramic sheets, Li 1.3 Al 0.3 Ti 1.7 (PO4)3 ceramic sheet, Li 10 GeP2S 12 Ceramic wafers, Li3PS4 ceramic wafers, Li7P3S 11 One or more of ceramic sheets and Li6PS5Cl ceramic sheets.

[0026] In this invention, the positive electrode in step 2) preferably includes one of lithium metal positive electrode, LiFePO4 positive electrode, LiCoO2 positive electrode and NCM811 positive electrode; the negative electrode preferably includes lithium metal negative electrode or silicon-carbon composite negative electrode.

[0027] In this invention, the coating method in step 2) preferably includes drop coating or immersion; the drop volume for drop coating is 0.005~0.50 mL / cm. 2 Preferably, the concentration is 0.01~0.30 mL / cm³. 2 More preferably, it is 0.02~0.10 mL / cm 2 More preferably, it is 0.03~0.05 mL / cm 2 The soaking time is 0.1~5 h, preferably 0.5~3 h, more preferably 0.8~2 h, and even more preferably 1 h.

[0028] The present invention also provides a lithium-ion battery based on an in-situ polymerized composite solid electrolyte prepared by the above-described method for preparing a lithium-ion battery based on an in-situ polymerized composite solid electrolyte.

[0029] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1

[0031] 1) Add LiTFSI, vinyl carbonate (VC), and Li7La3Zr2O 12 Powder (LLZO powder, average particle size 500 nm, conductivity 1×10⁻⁶) -3 The polymer precursor solution was obtained by mixing S / cm, azobisisobutyronitrile initiator (AIBN) and dimethyl carbonate (DMC) in a mass ratio of 15:10:35:0.75:10 and ultrasonically stirring for 10 min. 2) The polymer precursor solution obtained in step 1) is drop-coated onto lithium metal anode material, lithium metal cathode material, and Li7La3Zr2O. 12 The droplet application rate on the surface of the ceramic material (LLZO ceramic material) is 0.05 mL / cm. 2 This allows the polymer precursor solution to fully wet the interface, yielding Li7La3Zr2O. 12 Ceramic sheet, lithium metal positive electrode, and lithium metal negative electrode; 3) Sequentially add lithium metal anode, Li7La3Zr2O 12 Ceramic sheets and lithium metal cathodes were assembled and in-situ polymerized at 80°C for 4 h in a nitrogen atmosphere furnace. During this process, AIBN thermally decomposed to generate free radicals, which initiated VC polymerization and crosslinking, ultimately forming Li7La3Zr2O. 12 A dense polymer electrolyte interface layer is formed on the ceramic sheet and electrode surface, resulting in a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0032] Testing showed that the polymer electrolyte formed in the lithium-ion battery prepared in Example 1 has an ionic conductivity of 0.3 × 10⁻⁶ at room temperature. S / cm; and measurements using a Li|Li symmetric cell show that the interfacial impedance of the lithium-ion battery in Example 1 has decreased from the original 350 Ω·cm. 2 Reduced to 50 Ω·cm 2 The polarization voltage decreased significantly. At 0.5 mA / cm² 2 During a 1000-h constant current cycling test, the lithium-ion battery voltage of Example 1 remained stable below 50 mV with no short circuit observed, indicating interface stability. A 0.5 C cycle test was conducted using a Li metal / composite electrolyte / lithium cobalt oxide battery. The initial discharge capacity was 150 mAh / g, and after 100 cycles, the capacity retention was 95%, with a coulombic efficiency >99%. In summary, Example 1 achieves this by generating Li-rich electrolytes in situ at the LLZO-lithium metal interface. +The polymer layer effectively reduces interfacial impedance while maintaining high ionic conductivity.

[0033] Example 2

[0034] 1) Add LiPF6, polyethylene glycol diacrylate (PEGDA), and Li7La3Zr2O 12 Powder (LLZO powder, average particle size 500 nm, conductivity 1×10⁻⁶) -3 A polymer precursor solution was obtained by mixing a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) in a mass ratio of 15:11:35:1.25:15 with 1 / cm (S / cm), 1-hydroxycyclohexylphenyl ketone (Irgacure 184), and ethylene carbonate (EC) in a volume ratio of 1:1 (EC to DEC). 2) Integrating LiFePO4 cathode material and Li7La3Zr2O 12 The ceramic material was impregnated in the polymer precursor solution obtained in step 1) for 1 h to obtain LiFePO4 cathode and Li7La3Zr2O 12 Ceramic shards; 3) Sequentially add lithium metal anode, Li7La3Zr2O 12 The ceramic sheet and LiFePO4 cathode were assembled and irradiated under ultraviolet light (UV 365 nm) for 1 h to allow the PEGDA monomer to rapidly crosslink and polymerize at room temperature. The ultraviolet light excited Irgacure 184 to generate free radicals, which initiated the polymerization of acrylate to form a highly elastic crosslinked polymer layer (composite electrolyte), thus obtaining a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0035] Testing showed that the composite electrolyte formed in the lithium-ion battery prepared in Example 2 had an ionic conductivity of 2.0 × 10⁻⁶ at room temperature (25°C). -4 S / cm. The LiFePO4 / Li solid-state battery (mass loading of 10 mg / cm²) in Example 2 was tested at 0.2 C. The initial discharge capacity was 160 mAh / g, and it maintained more than 93% after 100 cycles, with a coulombic efficiency of 99.5%. Electrochemical impedance spectroscopy determined that the composite electrolyte / cathode interface impedance of the lithium-ion battery prepared in Example 2 was 250 Ω·cm before coating. 2 It dropped to 30 Ω·cm 2 This demonstrates that the in-situ polymer layer significantly improves the interfacial bonding of the battery.

[0036] Example 3

[0037] 1) LiPF6, 1,3-dioxolane (DOL, which can spontaneously ring-opening polymerize under conditions containing LiPF6), and Li7La3Zr2O 12Powder (LLZO powder, average particle size 500 nm, conductivity 1×10⁻⁶) -3 The polymer precursor solution was obtained by mixing (S / cm) and dimethyl carbonate (DMC) in a mass ratio of 20:15:27:20. 2) The polymer precursor solution obtained in step 1) is drop-coated onto the lithium metal anode material, the NCM811 cathode material, and Li7La3Zr2O. 12 The droplet application rate on the surface of the ceramic material (LLZO ceramic material) is 0.05 mL / cm. 2 This allows the polymer precursor solution to fully wet the interface, yielding Li7La3Zr2O. 12 Ceramic sheet, NCM811 positive electrode and lithium metal negative electrode; 3) Sequentially add lithium metal anode, Li7La3Zr2O 12 A semi-solid-state battery is obtained by assembling a ceramic sheet and an NCM811 cathode. A charging current (0.1 C) is applied for the first charging process. During this process, the electrochemical environment generated by the insertion of lithium ions into the NCM811 cathode and the Lewis acid effect of LiPF6 induce the spontaneous ring-opening polymerization of DOL monomers at the interface to form a polymer (polyoxymethylene carbonate). After 5 hours of polymerization, a dense polymer layer (composite electrolyte) is self-assembled at the interface, resulting in a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0038] Testing showed that the composite electrolyte formed in the lithium-ion battery prepared in Example 3 exhibited an ionic conductivity of 1.5 × 10⁻⁶ at room temperature (25°C). -4 S / cm; In Example 3, the NCM811 / Li all-solid-state battery exhibited an initial discharge capacity of 180 mAh / g in a 0.1 C charge-discharge test, retained 90% of its capacity after 200 cycles, and had a very low polarization voltage. AC impedance spectroscopy showed a significant decrease in interfacial impedance after electro-induced polymerization (from 500 Ω·cm before polymerization). 2 It dropped to 60 Ω·cm 2 This indicates that the composite electrolyte layer in Example 3 eliminates the gap between the electrode and the electrolyte and passivates the interfacial side reactions.

[0039] Example 4

[0040] 1) Add LiTFSI, polyethylene glycol diacrylate (PEGDA, molecular weight 700 g / mol), and Li7La3Zr2O 12 Powder (LLZO powder, average particle size 500 nm, conductivity 1×10⁻⁶) -3S / cm), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819) and dimethyl carbonate (DMC) were mixed in a mass ratio of 20:15:25:1:5 to obtain a polymer precursor solution; 2) The silicon-carbon composite anode material is immersed in the polymer precursor solution obtained in step 1) for 1 h to obtain the silicon-carbon composite anode; 3) Sequentially combine silicon-carbon composite anode, Li7La3Zr2O 12 The ceramic sheet and LiCoO2 cathode were assembled and irradiated under a 365 nm ultraviolet lamp for 2 h to form a polymer layer (composite electrolyte), thus obtaining a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0041] Testing showed that the composite electrolyte formed in the lithium-ion battery prepared in Example 4 had a conductivity of 2.8 × 10⁻⁶ at room temperature (25°C). -4 S / cm. The silicon-carbon composite anode / solid electrolyte / LiCoO2 cathode battery of Example 4 exhibited an initial reversible capacity of 900 mAh / g (based on Si mass) during 0.1 C cycling, retaining 80% of its capacity after 100 cycles. The apparent capacity decayed slowly, and the coulombic efficiency was >99%. Compared to the untreated battery, the composite electrolyte of Example 4 significantly suppressed the volume expansion effect of the silicon anode: the electrode structure remained intact after continuous cycling, without obvious pulverization cracks. This indicates that the elastic buffering effect of the polymer layer improved the mechanical contact between Si particles and maintained continuous Li... + Pathway; PEGDA has good affinity with Si and can form a passivation protective layer on the negative electrode surface.

[0042] Example 5

[0043] 1) Add LiPF6, 1,3-dioxolane (DOL), and Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder (LATP powder) and dimethyl carbonate (DMC) were mixed in a mass ratio of 20:15:27:20 to obtain a polymer precursor solution; 2) The polymer precursor solution obtained in step 1) is drop-coated onto the lithium metal anode material, the lithium metal cathode material, and the Li... 1.3 Al 0.3 Ti 1.7 The droplet application rate was 0.05 mL / cm² on the surface of (PO₄)₃ ceramic material (LATP ceramic material). 2 This allows the polymer precursor solution to fully wet the interface, yielding Li. 1.3 Al 0.3 Ti 1.7 (PO4)3 ceramic sheet, lithium metal positive electrode and lithium metal negative electrode; 3) The lithium metal anode, LATP ceramic sheet and lithium metal cathode are assembled sequentially to obtain a semi-solid battery. After charging and polymerization for 5 h with a charging current (0.1 C), a dense polymer layer (composite electrolyte) is formed at the interface, and a lithium-ion battery based on in-situ polymerized composite solid electrolyte is obtained.

[0044] Testing showed that the composite electrolyte formed in the lithium-ion battery prepared in Example 5 had a conductivity of 1.0 × 10⁻⁶ at room temperature (25°C). -4 S / cm; and the Li|Li symmetric cell in this embodiment 5 has a speed of 0.2 mA / cm. 2 No short circuit was observed after 400 hours of stable cycling.

[0045] This embodiment effectively isolates the direct contact between Li and LATP through in-situ polymer layer polymerization, thereby improving the stability of lithium-ion batteries.

[0046] Example 6

[0047] 1) Add LiTFSI, polyethylene glycol diglycidyl ether (polyepoxy ether), and Li 10 GeP2S 12 The powder (LGPS powder) and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure 2959) were mixed in a mass ratio of 20:15:25:1 to obtain a polymer precursor solution; 2) Li 10 GeP2S 12 The ceramic material and NCM811 cathode material were immersed in the polymer precursor solution obtained in step 1) for 1 h to obtain Li 10 GeP2S 12 Ceramic sheet (LGPS ceramic sheet) and NCM811 positive electrode; 3) The lithium metal anode, LGPS ceramic sheet and NCM811 cathode are assembled in sequence and irradiated under a 365 nm ultraviolet lamp for 2 h to form a polymer layer (composite electrolyte) and obtain a lithium-ion battery based on in-situ polymerized composite solid electrolyte.

[0048] Testing showed that the composite electrolyte formed in the lithium-ion battery prepared in Example 6 had a conductivity of 5 × 10⁻⁶ at room temperature. -4 S / cm (lower than pure LGPS due to the introduction of polymer-dispersed ions, but with significantly improved interfacial contact). The LGPS / NCM811 all-solid-state battery in Example 6 retained 86% of its capacity after 200 cycles at 0.5 C; compared to the pure LGPS interface, the interfacial impedance of the lithium-ion battery was reduced by 60%.

[0049] In summary, this invention utilizes an in-situ polymer layer to fill the voids between the inorganic electrolyte and the electrode, thereby improving interfacial affinity and ion conduction channels. Furthermore, lithium-ion batteries prepared using the method described in this invention all achieved a conductivity of 10⁻⁶ ppm at room temperature. -4 ~10 -3 With high ionic conductivity on the order of S / cm and significantly reduced interfacial impedance, it also exhibits good cycling stability under different electrode systems, showing broad application prospects.

[0050] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium ion battery based on in-situ polymerized composite solid-state electrolyte, characterized in that, The method comprises the following steps: 1) mixing a lithium salt, a polymerizable monomer and an inorganic filler to obtain a polymer precursor solution; 2) coating at least one of an inorganic solid-state electrolyte material, a positive electrode material and a negative electrode material with the polymer precursor solution to obtain an inorganic solid-state electrolyte, a lithium ion battery positive electrode and a lithium ion battery negative electrode; 3) sequentially assembling the lithium ion battery negative electrode, the inorganic solid-state electrolyte and the lithium ion battery positive electrode, and then performing in-situ polymerization to obtain a lithium ion battery based on an in-situ polymerization composite solid-state electrolyte; The inorganic filler in step 1) includes Li7La3Zr2O 12 powder, Li 1.3 Al 0.3 Ti 1.7 (PO4)3powder, Li 10 GeP2S 12 powder, Li3PS4powder, Li7P3S 11 powder, and Li6PS5Cl powder; The particle size of the inorganic filler is 200 nm to 2 μm; The in-situ polymerization in step 2) comprises thermal polymerization, photopolymerization or electro-polymerization; The temperature of the thermal polymerization is 50 to 120℃, and the time is 1 to 24 h; The ultraviolet wavelength of the photopolymerization is 320 to 400 nm, and the time is 10 to 120 min; The current of the electro-polymerization is 0 to 1 C, and the time is 0.5 to 10 h.

2. The method of claim 1, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The lithium salt in step 1) comprises one or more of LiTFSI, LiPF6 and LiFSI; The polymerizable monomer comprises one or more of vinyl carbonate, polyethylene glycol diacrylate, 1,3-dioxolane, ethyl acryloyloxyacetate, methacrylate and polyepoxy ether; The polyepoxy ether comprises one or more of polyethylene glycol diglycidyl ether, polyethylene oxide, polypropylene oxide, polybutylene oxide and poly(ethylene oxide-propylene oxide) block copolymer.

3. The method of claim 2, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The mass ratio of the lithium salt, the polymerizable monomer and the inorganic filler in step 1) is 5 to 30:5 to 30:10 to 50.

4. The preparation method of a lithium ion battery based on in-situ polymerization composite solid-state electrolyte according to any one of claims 1-3, characterized in that, The polymer precursor solution in step 1) further comprises an initiator and / or an organic solvent; The initiator comprises one or more of azobisisobutyronitrile, benzoyl peroxide, 1-hydroxycyclohexyl phenyl ketone, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone; The organic solvent comprises one or more of dimethyl carbonate, ethylene carbonate, diethyl carbonate and propylene carbonate.

5. The method of claim 4, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The mass ratio of the initiator and the organic solvent to the polymerizable monomer in step 1) is 0 to 2:0 to 30:5 to 30.

6. The method of claim 5, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The inorganic solid-state electrolyte in step 2) includes Li7La3Zr2O 12 ceramic sheet, Li 1.3 Al 0.3 Ti 1.7 ceramic sheet, Li 10 GeP2S 12 ceramic sheet, Li3PS4 ceramic sheet, Li7P3S 11 one or several of ceramic sheet and Li6PS5Cl ceramic sheet.

7. The method of claim 6, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The positive electrode in step 2) comprises one of a metal lithium positive electrode, a LiFePO4 positive electrode, a LiCoO2 positive electrode and a NCM811 positive electrode; The negative electrode comprises a metal lithium negative electrode or a silicon-carbon composite negative electrode.

8. The method of claim 7, wherein the in-situ polymerization of the composite solid-state electrolyte is carried out at a temperature of 20-80 °C. The coating method in step 2) comprises drop coating or immersion; The drop-coating dropwise amount is 0.005 to 0.50 mL / cm 2 ; The immersion time is 0.1 to 5 h.

9. A lithium ion battery based on an in-situ polymerization composite solid-state electrolyte prepared by the preparation method of the lithium ion battery based on an in-situ polymerization composite solid-state electrolyte in any one of claims 1 to 8.