Synthesis Of ?-Al₂O₃ Nanomaterial For Lithium Iron Battery

Lithium ion batteries have the advantages of high working voltage,large energy density,light weight,no pollution,and become the main power supply of many kinds of electronic products.But security is the bottleneck of the enlargement of lithium ion batteries.To improve the security of the battery and decrease the rate of internal short circuit,the ceramic coating on the surface of electrode or diaphragm is the most effective measure at present.?-Al₂O₃ materials have many excellent physico-chemical properties such as high mechanical strength,high hardness,high temperature resistance,good chemical stability,and are often used as Coating materials on the surface of anode or diaphragm of lithium ion batteries.Alumina precursor and ?-Al₂O₃ nanoparticle were prepared by chemical precipitation used aluminum nitrate and ammonia as raw materials.We studied how these factors?the concentration of raw materials,PH and dosage of dispersants?influenced the preparation of alumina precursor,and explored the effect of seed crystals on precursor calcination process.A kind of new isolation phase KCl was used to reduce the agglomeration of alumina precursor during the calcining process.The experimental results are as follows:?1?Alumina precursor was prepared by chemical precipitation used aluminum nitrate and ammonia as raw materials.We studied how these factors?the concentration of raw materials,PH and dosage of dispersants?influenced the morphology and particle size of alumina precursor.When other conditions remain unchanged,the average particle size of alumina precursor nanoparticles increased with the increasing Al?NO3?3 solution concentration.When other conditions remain unchanged,the average particle size of alumina precursor nanoparticles first increased and then decreased with the increasing dosage of dispersant PEG.The PH had great influence on the phase,morphology and particle size of alumina precursor.After the final optimization of preparation conditions,we synthesized ?-Al?OH?3 nanoparticles with 100 nm average particle size under the conditions of 0.10 mol/L Al?NO3?3 solution,0.5 g PEG and PH = 9.?2??-Al₂O₃ nanoparticles were used as seed crystal,and the addition of seed crystal was helpful for the dehydration reaction.During the calcination,?-Al?OH?3 nanoparticles went through the phase transition progress of ?-Al?OH?3??-AlOOH??-A12O3??-A12O3? ?-A12O3.Without the addition of seed crystal,?-Al₂O₃ phase completed the transformation at 1200 ?,and the particles were in the micron size.With the addition of seed crystal,?-Al₂O₃ phase completed the transformation at 1050 ?,the average size of ?-Al₂O₃ particles was 180 nm.The agglomeration of powder hadn't happened at this temperature.?3?KCl was innovatively added to the reaction system as a kind of calcination isolation phase at the molar ratio of KCl to Al₂O₃ 20:1.It's found that the addition of isolation phase had great influence on the particle size and morphology of the products.Finally the average width of about 100 nm fusiform ?-Al₂O₃ nanoparticles were prepared,as well as a few aggregate in the micron size.