A kind of fiber-reinforced polymer diaphragm for lithium iron phosphate battery and preparation method thereof

Abstract

The invention discloses fiber-reinforced polymer membrane for a lithium iron phosphate battery and a preparation method thereof. A width direction of the polymer membrane is a first direction. A length direction of the polymer membrane is a second direction. The polymer membrane comprises grid rib membrane (1). The grid rib membrane (1) comprises transverse ribs (1.1) and longitudinal ribs (1.2). The transverse ribs and the longitudinal ribs form grid holes (1.3). Fiber-directed non-woven fabric (2) is integrally formed in the grid rib membrane. The fiber-directed non-woven fabric comprises longitudinal high density fiber bundles (2.1) and transverse high density fiber bundles (2.2). The longitudinal high density fiber bundles cover the grid holes and are arranged along the first direction at intervals corresponding to the grid holes. The transverse high density fiber bundles cover the grid holes and are arranged along the second direction at intervals corresponding to the grid holes. Disordered nano-electrostatic spinning layers (3) are fixedly arranged at least one side of the high density fiber bundles in the grid holes. According to the fiber-reinforced polymer membrane for the lithium iron phosphate battery, the high-rate charge / discharge performance of the battery is greatly improved, and moreover, the polymer membrane has relatively high resistance to high temperature and relatively high security.

Description

technical field [0001] The invention relates to the technical field of diaphragms, in particular to a fiber-reinforced polymer diaphragm for lithium iron phosphate batteries and a preparation method thereof. Background technique [0002] Lithium battery separator is a porous insulating layer with a thickness of 8-40um. It prevents the contact between the positive electrode and the negative electrode in the battery, blocks the passage of electrons in the circuit during charging and discharging, and allows lithium ions in the electrolyte to pass through, thereby achieving ionization. The important role of conduction. The performance indicators of high-performance lithium battery separators are conflicting. For example, to improve the specific energy and high-power discharge capacity of lithium-ion batteries, it is necessary to increase the porosity of the separator and reduce the thickness of the separator in order to obtain a smaller ionic resistance, but These changes can g...

AI Technical Summary

Problems solved by technology

Due to the urgent needs of all walks of life for high-power, fast charge-discharge lithium-ion batteries, the prior art lithium battery separator has the following defects: poor temperature resistance, high temperature generated during transitional charge and discharge causes the separator to shrink or even melt, causing the electrode to directly Contact short circuit, and then cause a fire

However, due to the high molecular weight polyethylene used in the separator, the thermal shrinkage is relatively large, and the non-woven fabric made of electrospinning has no hindering effect on the thermal shrinkage, resulting in a relatively large thermal shrinkage of the battery separator as a whole.

[0005] There are also multilayer composite films in order to balance the performance of various aspects. Commonly used in the prior art are PP / PE composite films and PP / PE / PP composite films, which utilize polyethylene (PE) softness, good toughness, closed cell temperature and fusing The characteristics of low temperature also take advantage of the high mechanical properties of polypropylene, so that the lithium-ion battery separator has a lower closed cell temperature and a higher fusing temperature at the same time, but the PP / PE separator has poor affinity for the electrolyte. It is easy to tear long lines in an instant, and the short-circuit area expands rapidly in an instant. The sharply rising heat is difficult to discharge in time, and the potential explosion is relatively high.

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