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...

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