Method for preparing carbon-coated LiFePO4 anode material by using low-temperature solid-phase method

Abstract

The invention discloses a method for preparing a carbon-coated LiFePO4 anode material by using a low-temperature solid-phase method, comprising the following steps: 1, weighing iron phosphate and a lithium source based on the mole ratio of ferrum to lithium being 1: (1-1.05); weighing fatty acids in accordance with a ratio that 7.5-30g of fatty acids are added in per mole of iron phosphate; dissolving the weighed fatty acids in an organic solvent; and adding the weighed iron phosphate and the lithium source to the organic solvent of the fatty acids and then sufficiently mixing and grinding to obtain a precursor; and 2, carrying out calcination on the precursor obtained in the step 1 for 0.5-12 hours at a temperature of 400-700 DEG C under a non-oxide atmosphere and cooling to obtain the carbon-coated LiFePO4 anode material. The method is simple in operation without special equipment, and energy-saving and efficient due to carrying out the calcination once only. The method is used to obtain the carbon-coated LiFePO4 with even particle size distribution and good cyclical stability, which can be used as the anode material of a lithium ion secondary battery.

Description

technical field [0001] The invention belongs to the technical field of lithium ion secondary batteries, and in particular relates to a method for preparing a carbon-coated lithium iron phosphate cathode material. Background technique [0002] Lithium-ion secondary batteries have attracted widespread attention due to their good cycle performance, high voltage and energy density. Among them, the positive electrode material, as one of the keys affecting battery performance, has always been the focus of research. Lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide and multi-component composites are currently the main four cathode materials. With the continuous expansion of the application field of lithium-ion batteries, cathode materials need to have good cycle performance, high specific capacity, stable electrochemical performance, and low cost. Since cobalt is a scarce resource and is toxic, it is difficult to prepare lithium nickelate and multi-component com...

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Problems solved by technology

The hydrothermal carbonization method needs to be reacted in a high temperature and high pressure hydrothermal kettle, which is not conducive to continuous production; the carbothermal reduction method needs to be heated at 700 o It is carried out under high temperature and non-oxidizing atmosphere above C, and the product is easy to agglomerate, easy to produce impurity phases, and the product quality is difficult to control; the method of pyrolytic carbonization of organic carbon sources is to combine organic carbon sources, such as glucose, sucrose, polymers, and lithium organic carbon source, iron source and phosphorus source are mixed, and then pyrolytically carbonized in a non-oxidizing atmosphere to obtain carbon-coated lithium iron phosphate. However, due to the different thermal stability of organic carbon sources, the temperature of pyrolytic carbonization is also different. 600 o High temperature above C, and requires multiple calcinations and grindings, which consumes energy and time

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