Fluorinion-doped lithium iron phosphate material and preparation methods thereof

Abstract

The invention discloses a fluorinion-doped lithium iron phosphate material and preparation methods thereof. The fluorinion-doped lithium iron phosphate powder material has a chemical formula: LiFe(PO4)1-xF3x / C, wherein x is larger than 0 and smaller than 0.2. The fluorinion-doped lithium iron phosphate powder material can be prepared by two preparation methods of adding fluoride before pre-sintering and directly sintering or adding after pre-sintering and roasting fluoride, i.e. mixing lithium salt, iron salt and phosphate with fluoride, adding a carbon source, primarily mixing, pre-sintering and roasting or firstly mixing the lithium salt, the iron salt and the phosphate, adding the carbon source, mixing, pre-sintering, mixing with fluoride and roasting to obtain the fluorinion-doped lithium iron phosphate material. By adopting a low-temperature solid phase method, the fluorinion-doped lithium iron phosphate material is synthesized, an electrode material prepared by using the fluorinion-doped lithium iron phosphate material has excellent electrochemic performance and multiplication charging and discharging performance; the invention has the advantages of simple process, lower energy consumption and low raw material cost; and the obtained material has good electrochemic performance and excellent multiplication charging and discharging performance and is convenient for industrial mass production.

Description

technical field [0001] The invention relates to a lithium ion battery material, in particular to a fluoride-doped lithium iron phosphate material and a preparation method thereof, which can be used in lithium ion batteries, supercapacitors and capacitor batteries. Background technique [0002] Since 1997, J.B.Goodnough [J.Electrochem.Soc., 144 (1997) 1188] research group took the lead in synthesizing olivine-type LiFePO 4 And since it is used as a cathode material for lithium-ion batteries, LiFePO 4 Because of its stable structure, high specific capacity, long cycle life, low manufacturing cost, good safety performance, and environmental friendliness, it is considered to be an ideal cathode material for lithium-ion power batteries in the future. [0003] However, LiFePO 4 The low electronic conductivity and ion conductivity greatly limit its practical application in the field of lithium-ion power batteries. In order to overcome the above shortcomings of lithium iron phosp...

AI Technical Summary

Problems solved by technology

[0006] 1. Replacing oxygen ions in phosphate with fluoride ions requires huge energy consumption and is not easy to achieve

Even if the reaction is designed according to this idea, excess phosphorus will appear in the actual product obtained, and phosphorus will form phosphorus-iron compounds with iron, which will reduce the utilization rate of lithium iron phosphate active material

[0007] 2. Although the ball milling-rapid sintering method has a simple process, fluoride ions are mainly mixed in lithium iron phosphate in the form of fluoride, which only plays a role in coating modification; it is not doped into lithium iron phosphate, which is beneficial to the improvement of lithium iron phosphate. The ionic conductivity of the

[0008] 3. Pre-sintering and calcination temperature is too high

In addition, in actual production, too high a calcination temperature will increase the economic cost

Images