Ion liquid-based quasi-solid electrolyte for lithium battery and preparation method of quasi-solid electrolyte

Abstract

The invention relates to an ion liquid-based quasi-solid electrolyte for a lithium battery and a preparation method of the quasi-solid electrolyte, and belongs to the technical field of a lithium secondary battery. The quasi-solid electrolyte is of a porous network structure prepared by condensation reaction of a lithium salt, an ion liquid, a silane coupling agent and a catalyst and has high ion conductivity; the quasi-solid electrolyte can be used for stabilizing the stripping / deposition process of metal lithium and preventing lithium dentrites from growing, and shows relatively low overpotential and long-term cycle stability during the constant-current polarization process; and the interface impedance of a metal lithium sheet and the quasi-solid electrolyte is relatively small and is hardly increased with prolonging of the battery placement time. The preparation process of the quasi-solid electrolyte is simple, conventional equipment is used, the raw material is available, and the quasi-solid electrolyte is safe without pollution and is suitable for production on a large scale.

Description

technical field

[0001] The invention relates to an ionic liquid-based quasi-solid electrolyte for lithium batteries and a preparation method thereof, belonging to the technical field of lithium secondary batteries. Background technique

[0002] Lithium metal has the highest theoretical capacity (3860mAh / g) and extremely low reduction potential, making it an ideal negative electrode. Development of Li-S batteries and Li-O batteries using metallic lithium as a negative electrode pair 2 Batteries are critical. However, the formation of lithium dendrites and low Coulombic efficiency during the battery charge-discharge cycle seriously hinder the commercialization of metal lithium batteries. A stable lithium metal / electrolyte interface is a prerequisite for ensuring the safety and long cycle life of lithium metal batteries. One of the improvement strategies is to use solid-state electrolytes instead of liquid electrolytes, mainly to avoid the continuous side reactions of liquid...

Examples

Embodiment 1

[0032] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first place 0.91g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bistrifluoromethanesulfonimide salt, and stir for 24h to obtain ionic liquid electrolyte; then add 2.8g 3-methacryloyloxypropyl trimethoxy base silane and mix evenly; finally add 2.5mL formic acid with a purity greater than 98%, and continue stirring for 8min to obtain a reaction system;

[0033] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum oven with a relative vacuum of -80KPa, and dried at 50°C for 7 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0034] from figure 1 It can be seen from the SEM images in the figure that the surface of the quasi-solid electrolyte prepared in this embodiment is smooth without cracks. The resulting quasi-solid-state electrolyte was washed t...

Embodiment 2

[0037] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first put 1.82g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bistrifluoromethanesulfonimide salt, and stir for 24h to obtain an ionic liquid electrolyte; then add 0.7g 3-methacryloyloxypropyl trimethoxy base silane and 0.82g 3-methacryloxypropyltriethoxysilane and mix well; finally add 1.25mL formic acid with a purity greater than 98%, and continue stirring for 8min to obtain a reaction system;

[0038] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum drying oven with a relative vacuum of -100KPa, and dried at 70°C for 7 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0039] From the SEM image of the quasi-solid electrolyte prepared in this example, it can be seen that the prepared quasi-solid electrolyte has a smooth surface without cracks,...

Embodiment 3

[0042] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first place 4.368g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bis-trifluoromethanesulfonimide salt and 10.1g N-methyl, propylpiperidine bis-trifluoromethanesulfonimide salt, and stir for 24h to obtain Ionic liquid electrolyte; add 1.4g 3-methacryloxypropyltrimethoxysilane, 0.82g 3-methacryloxypropyltriethoxysilane and 0.65g γ-methacryloxy Propylmethyldimethoxysilane and mix well; finally add 1.62g of high-purity water, and continue to stir for 15min to obtain a reaction system;

[0043] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum oven with a relative vacuum of -90KPa, and dried at 90°C for 5 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0044] From the SEM image of the quasi-solid electrolyte prepared in this example, it can be see...

technical field

[0001] The invention relates to an ionic liquid-based quasi-solid electrolyte for lithium batteries and a preparation method thereof, belonging to the technical field of lithium secondary batteries. Background technique

[0002] Lithium metal has the highest theoretical capacity (3860mAh / g) and extremely low reduction potential, making it an ideal negative electrode. Development of Li-S batteries and Li-O batteries using metallic lithium as a negative electrode pair 2 Batteries are critical. However, the formation of lithium dendrites and low Coulombic efficiency during the battery charge-discharge cycle seriously hinder the commercialization of metal lithium batteries. A stable lithium metal / electrolyte interface is a prerequisite for ensuring the safety and long cycle life of lithium metal batteries. One of the improvement strategies is to use solid-state electrolytes instead of liquid electrolytes, mainly to avoid the continuous side reactions of liquid...

Examples

Embodiment 1

[0032] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first place 0.91g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bistrifluoromethanesulfonimide salt, and stir for 24h to obtain ionic liquid electrolyte; then add 2.8g 3-methacryloyloxypropyl trimethoxy base silane and mix evenly; finally add 2.5mL formic acid with a purity greater than 98%, and continue stirring for 8min to obtain a reaction system;

[0033] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum oven with a relative vacuum of -80KPa, and dried at 50°C for 7 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0034] from figure 1 It can be seen from the SEM images in the figure that the surface of the quasi-solid electrolyte prepared in this embodiment is smooth without cracks. The resulting quasi-solid-state electrolyte was washed t...

Embodiment 2

[0037] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first put 1.82g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bistrifluoromethanesulfonimide salt, and stir for 24h to obtain an ionic liquid electrolyte; then add 0.7g 3-methacryloyloxypropyl trimethoxy base silane and 0.82g 3-methacryloxypropyltriethoxysilane and mix well; finally add 1.25mL formic acid with a purity greater than 98%, and continue stirring for 8min to obtain a reaction system;

[0038] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum drying oven with a relative vacuum of -100KPa, and dried at 70°C for 7 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0039] From the SEM image of the quasi-solid electrolyte prepared in this example, it can be seen that the prepared quasi-solid electrolyte has a smooth surface without cracks,...

Embodiment 3

[0042] (1) In a glove box filled with argon gas with a purity greater than or equal to 99% and a moisture content of less than 1ppm, first place 4.368g LiN(SO 2 CF 3 ) 2 Dissolve in 4.6g N-methyl, propylpyrrolidine bis-trifluoromethanesulfonimide salt and 10.1g N-methyl, propylpiperidine bis-trifluoromethanesulfonimide salt, and stir for 24h to obtain Ionic liquid electrolyte; add 1.4g 3-methacryloxypropyltrimethoxysilane, 0.82g 3-methacryloxypropyltriethoxysilane and 0.65g γ-methacryloxy Propylmethyldimethoxysilane and mix well; finally add 1.62g of high-purity water, and continue to stir for 15min to obtain a reaction system;

[0043] (2) The reaction system obtained in step (1) was removed from the glove box, placed in a vacuum oven with a relative vacuum of -90KPa, and dried at 90°C for 5 days to obtain a quasi-solid electrolyte based on ionic liquid for lithium batteries.

[0044] From the SEM image of the quasi-solid electrolyte prepared in this example, it can be see...

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