Preparation method for lithium ion battery cathode material fluorine-doped lithium vanadate with circulatory stability

Abstract

The invention provides a preparation method for lithium ion battery cathode material fluorine-doped lithium vanadate with circulatory stability. The preparation method includes adding a vanadium source and a lithium source into deionized water to perform dispersion to obtain suspension A; adding complexing agent into the deionized water to obtain complexing agent liquor B; dripping the complexing agent liquor B into the suspension A to obtain clarified transparent liquor C; adding a fluorine source into the liquor C, and stirring, evaporating and drying the liquor C to obtain a blue lithium vanadate precursor; pre-sintering the blue lithium vanadate precursor in reducing atmosphere or inert atmosphere after grinding and smashing to obtain a grey lithium vanadate precursor; pre-sintering the grey lithium vanadate precursor in reducing atmosphere or inert atmosphere after grinding and smashing to obtain the fluorine-doped lithium vanadate. The preparation method has the advantages that fluorine doping and sintering are performed during complexometry-based lithium vanadate synthesis, and accordingly, electrochemical performance and electric conductivity of the material are improved.

Description

technical field [0001] The invention relates to the technical field of lithium battery preparation, in particular to a preparation method of fluorine-doped lithium vanadate, a lithium-ion battery negative electrode material with stable cycle. Background technique [0002] The development of new energy electric vehicles has drawn extensive attention to the research of power lithium-ion batteries, and continuously improving the safety performance and specific capacity of lithium-ion batteries has become a research hotspot. At present, the negative electrode material of power lithium-ion battery is mainly graphite material, but it only combines one Li per mole of C6. + The improvement of its capacity is limited, and at the same time, its lithium intercalation voltage is low, which is similar to the voltage of dendritic elemental lithium formed by the lithium ion lithium ion reaction, resulting in the formation of micro-short circuits inside the material, making lithium ions a...

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Problems solved by technology

(2) Alloy materials, mainly including Sn-based and Si-based materials; Sn-based and Si-based materials can be combined with multiple Li + Combined, the alloy material has a high capacity, but this type of material has a volume change of more than 300% during the electrochemical reaction, which causes the material to generate a large lattice stress during the cycle, causing the particle fragmentation of the material and from The current collector falls off, resulting in faster capacity decay and poor cycle performance of the material

(3) Transition metal oxide materials, such as Co 3 o 4 , Fe 3 o 4 etc.; the capacity of transition metal oxides is generally 2 to 3 times that of graphite materials, but the material becomes amorphous during the first discharge process, and the M-O metal bond is destroyed due to the effect of the energy barrier, which makes the material appear greatly Polarization phenomenon, low Coulombic efficiency and gradually increasing lithium intercalation voltage make transition metal oxide anode materials have great obstacles in practical application.

But Li 3 VO 4 It also has its own defects, and its electronic conductivity is very poor, which leads to its poor cycle stability during cycling

In order to improve Li 3 VO 4 The scientific community has conducted in-depth research on the cycle performance of Li 3 VO 4 Carbon coating treatment has been carried out, which has a good effect in improving the rate performance of the material, but the decay of the material is still relatively fast in terms of cycling; Li et al. (Adv.Sci.2015, 1500284) used a hydrothermal method to realize in-situ graphene Coating treatment can greatly improve the cycle performance of materials, but this method is not conducive to large-scale industrialization; and Chen et al. (Adv.Sci.2015,2,1500090) adopted the 3 VO 4 Amorphization treatment on the surface can improve the cycle performance of lithium vanadate to a certain extent, but this method cannot control the thickness of the surface amorphization of the material, and at the same time has high requirements for sintering equipment and consumes a lot of energy

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