Nanometer modification method of lithium iron phosphate and prepared nanometer modified lithium iron phosphate and lithium ion battery

Abstract

The invention provides a nanometer modification method of lithium iron phosphate and prepared nanometer modified lithium iron phosphate and a lithium ion battery, and relates to the technical field ofa lithium ion positive electrode material. According to the method, a lithium iron phosphate raw material and an optionally-added carbon source are mixed and subjected to ball milling to obtain lithium iron phosphate with nano-scale grain diameters; next, the nanometer lithium iron phosphate is subjected to spray granulation; and then the obtained nanometer lithium iron phosphate after spray granulation is roasted to prepare the nanometer modified lithium iron phosphate. The nanometer modified lithium iron phosphate has the advantages of large specific surface area and tiny granularity; and meanwhile, the nanometer modified lithium iron phosphate has very high tap density, and the material after granulation has more defects and micro pores, so that the electricity storage amount of the nanometer modified lithium iron phosphate is obviously improved. The prepared nanometer modified lithium iron phosphate can be widely applied to preparation of the positive electrode material of the lithium ion battery.

Description

technical field [0001] The invention relates to the technical field of lithium ion cathode materials, in particular to a nanometerized modification method of lithium iron phosphate and the prepared nanometerized modified lithium iron phosphate and lithium ion batteries. Background technique [0002] With the continuous development of human society, environmental problems have become increasingly prominent. In recent years, domestic smog has continued to intensify and people's expectations for environmental improvement have increased. With the rise of the national new energy strategy, lithium-ion batteries are used as a clean energy source. Small size, high energy density, safety and environmental protection, since the early 1990s, it has been widely used, and the cathode material as its main component has also made great progress. [0003] Lithium iron phosphate, as the positive electrode material of lithium-ion batteries, has a theoretical capacity of up to 170mAh / g. It was...

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Problems solved by technology

[0004] However, the ion conductivity and electron conductivity of the existing lithium iron phosphate materials are both low, and are only suitable for charging and discharging at low current densities. When charging and discharging at high rates, the specific capacity decreases and the tap density is low, which leads to The specific capacity of lithium iron phosphate is not high. Even if some manufacturers make high capacity, it is difficult to guarantee the stability between batches.

These disadvantages of lithium iron phosphate limit the application of this material

In order to improve the above defects, the technologies widely used at present mainly include the preparation of nano-scale lithium iron phosphate, the preparation of porous lithium iron phosphate, carbon coating, metal ion doping and other methods to modify lithium iron phosphate materials, but the common characteristics of these methods are The prepared lithium iron phosphate is relatively loose, and the tap density of the material is low, which affects the energy density of the power battery. Therefore, how to maintain a high tap density and compaction density while nanometerizing lithium iron phosphate has become a The essential

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