Diaphragm for secondary battery, preparation method of diaphragm and secondary battery

A secondary battery and diaphragm technology, applied in the field of secondary battery diaphragm and its preparation, can solve the problems of inability to carry out the combustion process of the electrolyte solution, reduce the ionic conductivity of the electrolyte solution, decrease the electrochemical performance, etc. Good cycle performance, preventing thermal runaway and explosion effects
CN114497891APending Publication Date: 2022-05-13惠州锂威电子科技有限公司
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
惠州锂威电子科技有限公司
Publication Date
2022-05-13

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Abstract

The invention provides a diaphragm for a secondary battery, a preparation method of the diaphragm and the secondary battery. The diaphragm comprises a base film and a flame-retardant layer coated on at least one surface of the base film, the flame-retardant layer is composed of a polyvinylidene fluoride-hexafluoropropylene binder and a flame-retardant capsule, and the flame-retardant capsule is of a core-shell structure with a flame retardant as an inner core and polymethyl methacrylate as an outer shell. Compared with the prior art, according to the diaphragm provided by the invention, when the battery is subjected to thermal runaway, the PMMA shell is broken and can release the flame retardant, the flame retardant can capture combustion free radicals and can effectively prevent thermal runaway and explosion of the battery, and the PMMA shell is adopted, so that better bonding force can be provided for the diaphragm and a pole piece; the problem that the cycle life of the battery is difficult to guarantee while the thermal runaway of the secondary battery is blocked at present is solved.
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Description

technical field

[0001] The invention relates to the field of secondary batteries, in particular to a diaphragm for a secondary battery, a preparation method thereof, and a secondary battery. Background technique

[0002] Lithium-ion batteries are considered to be the most promising power source for electric vehicles (EVs) due to their high specific energy density, lack of memory effect, and excellent cycling performance. However, due to the sharp increase in the energy density of lithium-ion batteries or the possibility of battery fire and explosion after a car collision, ensuring sufficient safety of lithium-ion batteries has become one of the most important issues at present. Studies have shown that the safety of lithium-ion batteries is closely related to the flammable components in the electrolyte and pole pieces. Once the inside / outside of the lithium-ion battery is on fire due to a short circuit, the flammable components (especially the cathode and flammable oxides of ...

Claims

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