Lithium iron phosphate composite pole piece and preparation method

Abstract

The invention discloses a preparation method of a lithium iron phosphate composite pole piece. The preparation method comprises the following steps: firstly dissolving lithium metal into liquid nitrogen to obtain a lithium sol solution, coating the lithium sol solution onto the surface of a spumy current collector, after pressing and high temperature treatment, coating a lithium iron phosphate sizing agent on the surface, and after drying, carrying out vapor deposition on the surface to obtain a graphene layer so as to obtain the positive composite pole piece. The preparation method is simplein process, high in efficiency and easy to control, solves the defects existing in a conventional pole piece coating technology, and is low in cost and excellent in effect. According to the obtained lithium iron phosphate composite pole piece, lithium supplementation is carried out on active substances through pre-lithiation of the current collector, so that the gram volume development and rate performance of a lithium iron phosphate battery can be improved, meanwhile, the cycle performance of the lithium ion battery is improved by using the characteristics that the electric conductivity of external graphene is high and the compatibility with an electrolyte is excellent.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery materials, in particular to a method for preparing a lithium iron phosphate composite pole piece, and the lithium iron phosphate composite pole piece obtained by the preparation method. Background technique [0002] With the increasing popularity of electric vehicles in the urban public transport system, in order to ensure the rapid development of urban public transport, higher requirements are put forward for the cruising range, fast charging capacity and service life of electric vehicles, and higher energy is required for lithium-ion batteries. Density, rate performance, cycle life and safety performance. Lithium iron phosphate material has become one of the ideal materials for lithium-ion batteries due to its long cycle life and high safety performance, and is widely used in pure electric vehicles, hybrid electric vehicles, etc., but due to the low energy density of lithium iron pho...

AI Technical Summary

Problems solved by technology

[0003] At present, the energy density of lithium iron phosphate batteries is mainly improved by using high-voltage electrolyte or high-capacity lithium iron phosphate cathode materials. Titanium, magnesium, and manganese crystals are integrated into the crystal structure of lithium iron phosphate, and then coated and sintered to increase the gram capacity and compaction density of the material. However, since the doping is achieved by solid grinding with a sand mill, the rate performance is general. , solid-phase method caused defects such as poor consistency

[0004] Pole piece coating technology, that is, to coat a substance on the surface of the pole piece to improve the energy density, safety performance and rate performance of the pole piece, is a new technology used to improve the energy density of the pole piece, mostly in the diaphragm and The surface of the positive pole piece and negative pole piece is coated to improve the electrochemical performance of the separator or pole piece. However, due to the difficult control of the coating process and the complicated process, the consistency of the material is often difficult to control, which limits the application of this technology.

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