Lithium battery diaphragm with overcharge protection function, and preparation method thereof

Abstract

The invention discloses a lithium battery diaphragm with an overcharge protection function, and a preparation method thereof. The battery diaphragm comprises a matrix and a functional coating which coats the surface of the matrix, and the functional coating comprises 5-15 wt% of poly(p-phenylene styrene) derivative, 30-50 wt% of polyacrylic acid, 1-5 wt% of a cross-linking agent and 40-60 wt% of polyvinyl alcohol. According to the invention, the functional coating with the overcharge protection function is constructed by virtue of the characteristics of reversible doping and impurity removal of the electroactive polymer poly(p-phenylene) derivative and reversible change of conductivity between a conductive state and an insulating state along with doping and impurity removal, the coating is formed on the surface of the diaphragm matrix in a dip-coating manner, and the diaphragm matrix is prepared into a lithium battery; p doping occurs under a high oxidation potential to become an electronic conductor, so that in an overcharge state, continuous rise of voltage is effectively prevented, overcharge is prevented, and the safety of the lithium battery in an overcharge environment is improved; and impurities are removed under normal working voltage to recover an electronic insulator, so that the performance of the lithium battery is not influenced.

Description

technical field

[0001] The invention relates to the technical field of new energy, in particular to a lithium battery diaphragm with an overcharge protection function and a preparation method thereof. Background technique

[0002] When large-capacity, high-power lithium batteries are widely used in electric vehicles, energy storage power stations and other fields, safety issues are becoming increasingly prominent. Its overcharging is one of the most dangerous factors leading to fire and explosion of lithium batteries.

[0003] Overcharge means that the charging voltage is higher than the charging cut-off voltage. In order to avoid over-discharging or over-charging of lithium batteries due to improper use, a protection mechanism is provided outside the lithium-ion battery. For example, if a safety valve is set, the internal pressure of the battery rises, and the safety valve opens automatically to ensure the safety of the battery; or a switching element is used. When the te...

Examples

Embodiment 1

[0028] (1) Prepare materials: weigh 10g of poly(p-phenylene vinylene derivative), 48g of polyacrylic acid, 2g of crosslinking agent, and 40g of polyvinyl alcohol for subsequent use;

[0029] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0030] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0031] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[003...

Embodiment 2

[0034] (1) Prepare materials: weigh 10g of poly(p-phenylene vinylene derivative), 43g of polyacrylic acid, 2g of crosslinking agent, and 45g of polyvinyl alcohol for subsequent use;

[0035] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0036] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0037] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[003...

Embodiment 3

[0040] (1) Prepare materials: weigh 10 g of poly(p-phenylene) derivatives, 38 g of polyacrylic acid, 2 g of crosslinking agent, and 50 g of polyvinyl alcohol for subsequent use;

[0041] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0042] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0043] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[0044] (...

technical field

[0001] The invention relates to the technical field of new energy, in particular to a lithium battery diaphragm with an overcharge protection function and a preparation method thereof. Background technique

[0002] When large-capacity, high-power lithium batteries are widely used in electric vehicles, energy storage power stations and other fields, safety issues are becoming increasingly prominent. Its overcharging is one of the most dangerous factors leading to fire and explosion of lithium batteries.

[0003] Overcharge means that the charging voltage is higher than the charging cut-off voltage. In order to avoid over-discharging or over-charging of lithium batteries due to improper use, a protection mechanism is provided outside the lithium-ion battery. For example, if a safety valve is set, the internal pressure of the battery rises, and the safety valve opens automatically to ensure the safety of the battery; or a switching element is used. When the te...

Examples

Embodiment 1

[0028] (1) Prepare materials: weigh 10g of poly(p-phenylene vinylene derivative), 48g of polyacrylic acid, 2g of crosslinking agent, and 40g of polyvinyl alcohol for subsequent use;

[0029] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0030] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0031] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[003...

Embodiment 2

[0034] (1) Prepare materials: weigh 10g of poly(p-phenylene vinylene derivative), 43g of polyacrylic acid, 2g of crosslinking agent, and 45g of polyvinyl alcohol for subsequent use;

[0035] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0036] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0037] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[003...

Embodiment 3

[0040] (1) Prepare materials: weigh 10 g of poly(p-phenylene) derivatives, 38 g of polyacrylic acid, 2 g of crosslinking agent, and 50 g of polyvinyl alcohol for subsequent use;

[0041] (2) Preparation of slurry: dissolve the above materials into dichloromethane, set the dissolution temperature to 5°C, and the stirring speed during dissolution is 250rpm, and prepare a slurry with a viscosity of 300mPa·s;

[0042] (3) Dip coating: the substrate is immersed in the coating tank, the angle of immersion and extraction is 45°, the immersion speed is set to be 30cm / min, and the transfer roller is extracted to form coating A and obtain diaphragm B;

[0043] (4) Cross-linking: Send the diaphragm B into the hot air channel, dichloromethane volatilizes into the recovery system, and the coating forms a cross-linking structure under the action of the cross-linking agent. Set the cross-linking temperature to 90°C and the cross-linking time to 25 minutes , to obtain diaphragm C;

[0044] (...

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