Tertiary aniline-based polymer material applied to battery and application of tertiary aniline-based polymer material

Abstract

The invention discloses a tertiary aniline polymer material applied to a battery and application of the tertiary aniline polymer material. The tertiary aniline polymer material has good interfacial compatibility to a positive electrode and a negative electrode of the battery. According to the tertiary aniline polymer material provided by the invention, the room-temperature ionic conductivity is greater than or equal to 10 <-4 > S / cm, the electrochemical stability window is greater than or equal to 4.5 V (vs. Li / Li < + >), compact and uniform solid electrolyte interface layers (SEI) can be simultaneously formed on the surfaces of a positive electrode and a negative electrode, and parasitic reaction is reduced. In addition, the conjugation effect in the tertiary aniline functional group enables pi electrons to move freely, dissociation of the lithium salt is further promoted, and the ionic conductivity of the system is improved. The tertiary aniline polymer material is applied to battery systems including lithium ion batteries and lithium metal batteries, and due to high lithium ion conductivity, high tensile strength and good interface compatibility, the safety performance of quasi-solid-state batteries can be improved, and the cycle life of the quasi-solid-state batteries can be prolonged.

Description

Technical Field

[0001] The invention belongs to the field of energy storage and conversion materials, and in particular relates to a tertiary aniline-based polymer material used in batteries and an application thereof. Background Art

[0002] The rapid development of electric vehicles, large-scale grid storage and consumer electronics industries has put forward higher requirements for the energy density and safety of lithium batteries. At present, traditional lithium-ion batteries use organic liquid electrolytes, whose good fluidity can infiltrate porous electrodes, thereby constructing a continuous channel for lithium ion conduction in the battery, and are therefore widely used in energy storage and conversion devices. However, during the charging and discharging process of the battery, the electrolyte is prone to side reactions with the positive and negative electrodes, causing the battery to easily experience irreversible capacity decay and serious safety hazards. In comparison, polymer lithium-ion conductor materials composed of polymer matrix, solvent and lithium salt have the advantages of good flexibility and plasticity, easy packaging, and a wide operating temperature range, and are expected to completely solve the safety problems of batteries.

[0003] However, common polymer lithium ion conductor materials, such as ether-based, ester-based, fluorine-based, and nitrile-based polymers, when assembled with positive and negative electrodes, still have problems such as serious interface parasitic reactions between polymers and electrodes and lithium dendrite growth under long-term service conditions, causing electrode interface degradation and leading to rapid battery cycle decay. For example, Teeters et al. [SolidState Ionics, 2000, 135: 283] combined infrared spectroscopy and atomic force microscopy to deeply study the interface reaction process between polyethylene oxide-trifluoromethanesulfonate polymer ion conductor and lithium negative electrode, and found that lithium trifluoromethanesulfonate first reacts with lithium metal to produce CF 3 Free radicals, which can quickly capture hydrogen atoms on the polymer main chain and destroy the CO bonds on the polymer main chain to form Li-OR type compounds, leading to the decomposition of polymer segments and accelerating the degradation of the lithium negative electrode interface. At the same time, lithium dendrites can pierce the battery separator, causing the negative electrode to directly contact the positive electrode, causing the battery to short-circuit and fail. Therefore, there is an urgent need to develop polymer lithium ion conductor materials with high lithium ion conductivity and high electrode interface compatibility, which will provide key materials for the design and development of high energy density and high safety lithium ion batteries, lithium metal batteries, lithium sulfur batteries and lithium air batteries.

[0004] This application presents a unique and simple strategy. By introducing a polymer lithium-ion conductor material containing a tertiary aniline group into the battery system as a quasi-solid electrolyte or an electrode interface protective layer, the chemical / electrochemical stability of the battery during cycling is significantly improved. The abundant tertiary aniline groups in N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and 4-glycidyloxy-N,N-diglycidylaniline have high reactivity and can preferentially form a stable solid electrolyte interface layer rich in N-C 3 derivatives on the electrode surface, enhancing the interfacial compatibility between the electrolyte and the electrode. In addition, the conjugated effect in the tertiary aniline functional group enables the free movement of π electrons, further promoting the dissociation of lithium salts and increasing the ionic conductivity of the system, providing key materials for the construction of high-performance lithium batteries. Summary of the Invention

[0005] The object of the present invention is to provide a tertiary aniline-based polymer material with high ionic conductivity, high mechanical stability, and high electrode compatibility, as well as its applications as an electrode interface protective layer and an electrolyte in batteries.

[0006] A tertiary aniline-based polymer material for use in batteries provided by the present invention is obtained through the following process: at least one of the two monomers N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and 4-glycidyloxy-N,N-diglycidylaniline is added to an organic solvent to obtain a mixed solution, a lithium salt and an initiator are added, and after heating for a certain time, the tertiary aniline-based polymer material is obtained. The volume ratio of the monomer in the two compounds of the monomer and the organic solvent is 1% - 50%.

[0007] The lithium salt described in the present invention contains a boron group, an imine group, a sulfonic acid group, or a phosphoric acid group, with a relative molecular mass greater than 93 and less than 740. And it is particularly preferably at least one of the following substances: lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(perfluoromethylpinacolato)borate, lithium bis(oxalato)borate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium tris(trifluoromethanesulfonyl)methyl, and lithium bis(oxalato)borate. The concentration of the lithium salt in the mixed solution is 0.5 - 3 mol L -1 .

[0008] The initiator described in the present invention is one or a mixture of two or more in any proportion selected from lithium difluorooxalate borate, boron trifluoride, tin difluoride, tris(pentafluorophenyl)borane, aluminum trifluoromethanesulfonate, lithium hexafluorophosphate, and aluminum fluoride. The concentration of the initiator in the mixed solution is 0.001 - 1 mol L -1 .

[0009] The organic solvents in the present invention are one or a mixture of two or more of tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether, dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, dimethyl carbonate, diethyl carbonate, propylene carbonate, and 1-methylimidazole, and the organic solvent accounts for 50-99% of the total volume of the tertiary aniline monomer and the organic solvent.

[0010] The heating in the present invention means heating to 40-80 °C, and the heating time is 0.2-12 h.

[0011] A tertiary aniline-based polymer material in the present invention is used as a surface protective layer on the positive or negative electrode of a lithium-ion battery, a lithium metal battery, a lithium-sulfur battery, or a lithium-air battery; or as an electrolyte of a battery.

[0012] When the tertiary aniline-based polymer material in the present invention is used as a surface protective layer on the positive or negative electrode, the addition amount of the tertiary aniline-based polymer material is 1-40 μL / cm 2 . After addition, it needs to be dried at 40-80 °C for more than 6 h.

[0013] When the tertiary aniline-based polymer material in the present invention is used as an electrolyte of a battery, the tertiary aniline-based polymer precursor is dropped onto the separator, and the dropping amount is 20-150 μL / cm 2 , and after assembling the battery, it is heated at 40-80 °C for 0.2-12 h.

[0014] The present invention has the following advantages: The present invention uses at least one of N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and 4-glycidyloxy-N,N-diglycidylaniline as a multifunctional crosslinking monomer to prepare a tertiary aniline-based polymer material. Among them, the tertiary aniline functional group has a narrow frontier orbital energy level difference, so it shows high reactivity and can react on the surfaces of both the positive and negative electrodes to form a dense and uniform solid electrolyte interface layer rich in N-C 3 derivatives. In addition, the conjugation effect in the tertiary aniline functional group enables π electrons to move freely, making the entire functional group have a strong electron-donating ability, enhancing its coordination ability with lithium ions, and thus promoting the dissociation of lithium salts. The organic solvent with a high dielectric constant and DN value further accelerates the dissociation of lithium salts, making the tertiary aniline-based polymer material have a strong ability to dissociate lithium salts and coordinate lithium ions. Description of the Drawings

[0015] Figure 1 Scanning electron microscope image of the tertiary aniline-based polymer material prepared in Example 1 on the negative electrode surface.

[0016] Figure 2Scanning electron microscope image of the polymer material prepared in Comparative Example 1 on the surface of the negative electrode.

[0017] Figure 3 Curve of the ionic conductivity of the tertiary aniline-based polymer material prepared in Example 2 varying with temperature.

[0018] Figure 4 Linear sweep voltammetry curve of the tertiary aniline-based polymer material prepared in Example 2.

[0019] Figure 5 Curve of the ionic conductivity of the polymer material prepared in Comparative Example 2 varying with temperature.

[0020] Figure 6 Linear sweep voltammetry curve of the polymer material prepared in Comparative Example 2.

[0021] Figure 7 Transmission electron microscope image of the tertiary aniline-based polymer material prepared in Example 3.

[0022] Figure 8 N 1s X-ray photoelectron spectroscopy of the tertiary aniline-based polymer material prepared in Example 3.

[0023] Figure 9 Cycling performance curve of the tertiary aniline-based polymer material prepared in Example 4 in the battery. Detailed implementation mode

[0024] In order to make the technical objectives, technical solutions and good effects of the present invention clearer, the following will be described in more detail through examples, but the protection scope of the present invention is not limited to the examples.

[0025] Example 1: (1) Mix 4-glycidyloxy-N,N-diglycidylaniline with propylene carbonate at a volume ratio of 1:99 to obtain a mixed solution A.

[0026] (2) Add lithium salt lithium bis(trifluoromethanesulfonyl)imide and initiator tris(pentafluorophenyl)borane to the mixed solution A, and heat at 40 °C for 6 h to obtain the tertiary aniline-based polymer material. The concentration of the lithium salt in the mixed solution A is 0.5 mol / L -1 , and the concentration of the initiator in the mixed solution A is 0.001 mol / L -1 .

[0027] (3) Respectively take the above-mentioned tertiary aniline-based polymer material and drop it on the lithium iron phosphate positive electrode (using aluminum foil as the current collector and the lithium iron phosphate loading is 3.5 mg / cm -2 ) and the lithium metal negative electrode, the dropping amount is 20 μL / cm 2 , and dry at 60 °C for 6 h to form an interfacial protection layer.

[0028] The microscopic morphology of the tertiary aniline-based polymer material obtained in Example 1 on the surface of the lithium metal anode is as Figure 1 shown. It can be seen from the figure that the tertiary aniline-based polymer material is a dense and uniform thin film on the surface. An all-solid-state battery was assembled using an electrode with an electrode interface protection layer, a PP separator, and a propylene carbonate electrolyte containing 0.5 mol L -1 lithium bis(trifluoromethanesulfonyl)imide. At 25 °C and 1C, the initial discharge specific capacity is 149.7 mAh g -1 , and the capacity retention rate is 94.9% after 500 cycles.

[0029] Comparative Example 1: (1) Glycerol triglycidyl ether and propylene carbonate were mixed at a volume ratio of 1:99 to obtain a mixed solution B.

[0030] (2) Lithium salt lithium bis(trifluoromethanesulfonyl)imide and initiator tris(pentafluorophenyl)borane were added to the mixed solution B, and after heating at 40 °C for 12 h, the tertiary aniline-based polymer material was obtained. The concentration of the lithium salt in the mixed solution B is 0.5 mol L -1 , and the concentration of the initiator in the mixed solution B is 0.001 mol L -1 .

[0031] (3) The above-mentioned polymer materials were respectively dropped onto the lithium iron phosphate cathode and the lithium metal anode, and the dropping amount was 20 μL / cm 2 , and an interface protection layer was formed after sufficient drying.

[0032] The microscopic morphology of the polymer material obtained in Comparative Example 1 on the surface of the lithium metal anode is as Figure 2 shown. It can be seen from the figure that the polymer material is unevenly distributed on the anode surface and segregation occurs. Different from Example 1, the polymer in Comparative Example 1 does not have highly reactive tertiary aniline groups, so the polymer cannot adhere to the anode surface evenly, which is a common problem in the current polymer system. The electrode with an interface protection layer prepared in Comparative Example 1 was assembled with a PP separator and a propylene carbonate-based electrolyte containing 0.5 mol L -1 lithium bis(trifluoromethanesulfonyl)imide to form an all-solid-state battery. At 25 °C and 1C, the initial discharge specific capacity is 141.2 mAh g -1 , and the capacity retention rate is 51.2% after 500 cycles. The cycling performance is much worse than that of the tertiary aniline-based polymer material prepared by the method of the present invention in Example 1.

[0033] Example 2: (1) N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and ethylene glycol dimethyl ether were mixed at a volume ratio of 1:15 to obtain a mixed solution A.

[0034] (2) Lithium salt lithium bis(oxalato)borate and initiator stannous difluoride are added to the mixed solution A to obtain a mixed solution B. The concentration of the lithium salt in the mixed solution A is 3 mol / L -1 , and the concentration of the initiator in the mixed solution A is 0.05 mol / L -1 .

[0035] (3) Take the above-mentioned mixed solution B and drop it on the PP film, and the dropping amount is 150 μL / cm 2 , and assemble it with a sulfur positive electrode (using aluminum foil as the current collector and the sulfur loading is 3.5 mg / cm -2 ) and a lithium metal negative electrode. After assembling the battery, heat it at 80 °C for 0.2 h to obtain a battery using the tertiary aniline-based polymer material as the quasi-solid electrolyte.

[0036] The curve of the ionic conductivity of the tertiary aniline-based polymer material obtained in Example 2 versus temperature is as Figure 3 shown. It can be seen from the figure that at room temperature, the ionic conductivity of this tertiary aniline-based polymer material is 6.7×10 -4 S / cm -1 . The linear sweep voltammetry curve of the tertiary aniline-based polymer material obtained in Example 2 is as Figure 4 shown. It can be seen from the figure that the electrochemical stability window of this tertiary aniline-based polymer material is 5.0 V.

[0037] Comparative Example 2: (1) 1,3-Dioxolane and ethylene glycol dimethyl ether are mixed at a volume ratio of 1:15 to obtain a mixed solution C.

[0038] (2) Lithium salt lithium bis(oxalato)borate and initiator stannous difluoride are added to the mixed solution C to obtain a mixed solution D. The concentration of the lithium salt in the mixed solution C is 3 mol / L -1 , and the concentration of the initiator in the mixed solution C is 0.05 mol / L -1 .

[0039] (3) Take the above-mentioned mixed solution D and drop it on the PP film, and the dropping amount is 150 μL / cm 2 , and assemble it with a sulfur positive electrode and a lithium metal negative electrode. After assembling the battery, heat it at 80 °C for 0.2 h to obtain a battery using the polymer material as the quasi-solid electrolyte.

[0040] The curve of the ionic conductivity of the polymer material obtained in Comparative Example 2 versus temperature is as Figure 5 shown. It can be seen from the figure that at room temperature, the ionic conductivity of this polymer material is 1.2×10 -4 S / cm -1 . The linear sweep voltammetry curve of the polymer material obtained in Comparative Example 2 is as Figure 6As shown, it can be seen from the figure that the electrochemical stability window of the polymer material is 4.1 V. The difference between Comparative Example 2 and Example 2 is that: the polymer material in Comparative Example 2 does not contain a tertiary aniline functional group.

[0041] Example 3: (1) Mix N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and sulfolane in a volume ratio of 1:1 to obtain a mixed solution A.

[0042] (2) Add lithium salt bis(perfluoromethylpinacolato)borate lithium and initiator lithium difluorooxalate borate to the mixed solution A to obtain a mixed solution B. The concentration of the lithium salt in the mixed solution A is 1 mol L -1 , and the concentration of the initiator in the mixed solution A is 1 molL -1 .

[0043] (3) Take the above mixed solution B and drop it on the PP film, and the dropping amount is 50 μL / cm 2 , and assemble it with a lithium cobalt oxide positive electrode (using aluminum foil as the current collector and the lithium cobalt oxide loading amount is 3.5 mg cm -2 ), and a graphite negative electrode. After assembling the battery, heat it at 60 °C for 4 h to obtain a battery using a tertiary aniline-based polymer material as a quasi-solid electrolyte.

[0044] The transmission electron microscope image of the positive electrode particles in the battery assembled with the tertiary aniline-based polymer material obtained in Example 3 is as shown in Figure 7 . It can be seen from the figure that a dense and uniform solid electrolyte interface layer is formed on the surface of the positive electrode. The X-ray photoelectron spectroscopy of the solid electrolyte interface layer formed by the tertiary aniline-based polymer material obtained in Example 3 on the positive electrode is as shown in Figure 8 . It can be seen from the figure that this interface layer contains rich N-C 3 derivatives.

[0045] Example 4: (1) Mix N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether, 4-glycidyloxy-N,N -diglycidylaniline with N,N-dimethylformamide and 1-methylimidazole in a volume ratio of 1:10 to obtain a mixed solution A.

[0046] (2) Add lithium salt lithium trifluoromethanesulfonate and initiator lithium hexafluorophosphate to the mixed solution A to obtain a mixed solution B. The concentration of the lithium salt in the mixed solution A is 1.5 mol L -1 , and the concentration of the initiator in the mixed solution A is 0.3 mol L -1 .

[0047] (3) Take the above mixed solution B and drop it on the PP film, and the dropping amount is 20 μL / cm 2 , and assemble it with LiNi0.8 Mn 0.1 Co 0.1 O 2 The positive electrode (using aluminum foil as the current collector, LiNi 0.8 Mn 0.1 Co 0.1 O 2 with a loading of 3.5 mg cm -2 ), and the lithium metal negative electrode are assembled into a battery and heated at 50 °C for 3 h to obtain a battery using the tertiary aniline-based polymer material as the quasi-solid electrolyte.

[0048] The cycle performance curve of the battery assembled with the tertiary aniline-based polymer material obtained in Example 4 is as Figure 9 shown. It can be seen from the figure that at 25 °C and 0.5C, the initial discharge specific capacity is 181.2 mAh g -1 , and after 1200 cycles, the discharge specific capacity is 145.1 mAh g -1 , and the capacity retention rate is 80.1%.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tertiary aniline-based polymer material for battery, characterized in that: The method is obtained by the following process: at least one of two monomers, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether and 4-epoxypropyloxy-N,N-diglycidylaniline, is added into an organic solvent to obtain a mixed solution, a lithium salt and an initiator are added to obtain a tertiary aniline polymer precursor, and the tertiary aniline polymer material is obtained after heating for a certain period of time, wherein the volume ratio of the monomer in the two compounds of the monomer and the organic solvent is 1%-50%.

2. The tertiary aniline-based polymer material for battery according to claim 1, characterized in that: The lithium salt used is at least one of lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(pertrifluoromethylpinacol)borate, lithium bis(oxalate borate), lithium trifluoromethanesulfonate, lithium bis(trifluoromethylsulfonyl)imide, tris(trifluoromethylsulfonyl)methyl lithium and lithium bis(oxalate borate), and the concentration of the lithium salt in the mixed solution is 0.5-3 mol L -1 .

3. The tertiary aniline-based polymer material for battery according to claim 1, characterized in that: The initiator is one or a mixture of any proportion of lithium difluorooxalatoborate, boron trifluoride, tin difluoride, tri(pentafluorophenyl)borane, aluminum trifluoromethanesulfonate, lithium hexafluorophosphate and aluminum fluoride. The concentration of the initiator in the mixed solution is 0.00 ~1 mol L -1 .

4. The tertiary aniline-based polymer material for battery according to claim 1, characterized in that: The organic solvent is one or a mixture of any proportion of tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether, dimethyl sulfoxide, cyclopentane, N,N-dimethylformamide, dimethyl carbonate, diethyl carbonate, propylene carbonate and 1-methylimidazole, and the organic solvent accounts for 50-99% of the volume of the tertiary aniline monomer and the organic solvent.

5. The tertiary aniline-based polymer material for battery according to claim 1, characterized in that: The heating refers to heating to 40-80°C for a heating time of 0.2-12 h.

6. Use of the tertiary aniline-based polymer material for battery according to any one of claims 1 to 5 in a lithium battery.

7. The use according to claim 6, characterized in that: Used as a surface protective layer for the positive electrode or negative electrode of a lithium-ion battery, a lithium metal battery, a lithium sulfur battery or a lithium air battery; or used as an electrolyte for a battery.

8. The use according to claim 7, characterized in that: When the surface protective layer of the positive electrode or the negative electrode is formed, the amount of the tertiary aniline polymer material added is 1-40 μL / cm 2 .

9. The use according to claim 7, characterized in that: When used as a battery electrolyte, the tertiary aniline polymer precursor is dripped onto the separator in an amount of 20-150 μL / cm 2 After assembling the battery, heat it at 40~80℃ for 0.2~12h.

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