Method for preparing lithium iron phosphate cathode material with high-compaction and high-rate performance

Abstract

The invention discloses a method for preparing a lithium iron phosphate cathode material with high-compaction and high-rate performance, and relates to the technical field of lithium ion battery cathode materials. The method comprises the following steps of: according to a mass ratio of 100:4.5:(0.5-4), adding and dispersing a layered mesoporous graphite phase carbon nitride powder g-C3N4, PVP anda carbohydrate to deionized water to obtain a dispersion A; weighing FePO4 according to a mass ratio of FePO4:g-C3N4=50:(0.8~1.5), and adding and dispersing the FePO4 to the dispersion A to obtain adispersion B; weighing a lithium source according to a stoichiometric ratio of Fe:Li=1:1, and adding and dispersing the lithium source to the dispersion B to obtain a dispersion C; ultrafine grindingthe dispersion C, spray-drying the dispersion C, and then presintering and sintering the dispersion C under a protective atmosphere, naturally cooling a product so as to obtain the lithium iron phosphate cathode material. The method uses the g-C3N4 as a layered template and a main carbon source, and uses the excellent dispersing property of the PVP for shape control and modification in the processof lithium iron phosphate, thereby greatly improving the compaction and charge-discharge rate performance of the lithium iron phosphate cathode material.

Description

technical field [0001] The invention relates to the technical field of cathode materials for lithium ion batteries, in particular to a preparation method of a high-compaction and high-rate performance lithium iron phosphate cathode material. Background technique [0002] In recent years, with the increasing impact of fossil energy on the earth's environment, clean energy has been promoted as an alternative. As a representative of clean energy, new energy batteries are gradually becoming the first choice for passenger cars, buses and energy storage businesses. Lithium iron phosphate battery has become the current new energy due to its low price, high theoretical capacity (about 170mAh / g), stable working voltage, non-toxic and environmentally friendly, stable structure, good safety performance, good thermal stability and long cycle life Hotspot of battery research. As far as the currently developed lithium iron phosphate products are concerned, the material still has disadva...

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Problems solved by technology

As far as the currently developed lithium iron phosphate products are concerned, the material still has disadvantages such as low ion conductivity, poor electrical conductivity, low compaction density, and poor low-temperature performance, which lead to problems such as low energy density and poor processability, which limit the Its wide application in power battery

[0003] In response to the above problems, relevant researchers have improved the rate performance or compaction of the material by nano-processing and carbon-coating lithium iron phosphate materials, but most of them can only meet a single high rate or high compaction performance. It is difficult to achieve high compaction and high ratio at the same time, and there are problems such as uneven carbon coating of materials and poor machinability

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