Study On The Physical And Chemical Changes Of LiNi_0.5Co_0.2Mn_0.3O₂ Precursor And Refractory Raw Materials Used By Saggar In The Heating Process

We studied the ternary,binary and ternary refractory raw materials used in saggers and Li Ni_0.5Co_0.2Mn_0.3O₂?LNCM?precursor and the effects of the ratio of LNCM precursor and refractory raw materials,holding time and particle size of the refractory raw materials on the reaction were also studied.By using X-ray diffractometer to analyze the phase composition of the sample after heat treatment at different temperatures,the microstructure of the sample after heat treatment was observed by Scanning Electron Microscope,and analyze and the elemental composition of the micro area was identified by Energy Dispersive Spectrometer.The conclusions are as follows:?1?By studying the precursor synthesis of LNCM,the phase composition of the precursor is spherical Ni_0.5Co_0.2Mn_0.3?OH?₂ and long-columnar Li₂CO₃.After the precursor calcined at 500?,most of Li₂CO₃ and Ni_0.5Co_0.2Mn_0.3?OH?₂ reacted to form LNCM.With the increase of temperature,the precursors calcined at 750?,900? and1000?,and the grains on the surface of the spherical particles gradually grow.?2?The physical and chemical reactions of LNCM precursor with aluminum oxide,silicon oxide,and magnesium oxide during the heating process were studied.LNCM reacted with aluminum oxide and silicon oxide at 750?,LNCM and aluminum oxide produced a small amount of?-Li Al O₂,Co Al₂O₄,Ni Al₂O₄,?-Li Al O₂ and Li Mn₂O₄.LNCM reacted with silicon oxide to produce a small amount of Li₂Si O₃;as the temperature rises,at 900?,the amount of product increased,?-Li Al O₂ produced by the reaction of LNCM with alumina is converted into?-Li Al O₂,LNCM reacted with silicon oxide to form Li₂Si₃O₅,Co₂Si O₄,Ni₂Si O₄ and Li Mn₂O₄,LNCM reacted completely;at 1000?,the type of product remained the same,the amount of production increased,LNCM reacted with alumina with a small amount of LNCM remaining,when LNCM reacted with silicon oxide,a part of silicon oxide was transformed into cristobalite.From the microstructure,the product grains that formed on the surface of aluminum oxide and silicon oxide gradually grew with increasing temperature,at 1000?,there was a glass phase in the silicon oxide sample.LNCM precursor and magnesium oxide were calcined at 500?,750?,900? and 1000? without reaction.?3?By studying the physical and chemical reactions of LNCM precursor with mullite,andalusite,magnesium-aluminate spinel,zircon,and forsterite during the heating process.LNCM reacted with mullite,andalusite and magnesia-alumina spinel at 900?,LNCM reacted with mullite to form Co Al₂O₄,Ni₂Si O₄,Li Al Si O₄,Li₂Si O₃and Li Mn₂O₄,LNCM reacted with andalusite to form Li Al Si O₄,Co Al₂O₄,Ni₂Si O₄,Li Mn₂O₄ and Co₂Si O₄,LNCM and magnesium aluminum spinel were formed Li Mn₂O₄,Co Al₂O₄,Ni Al₂O₄ and?-Li Al O₂;as the temperature increases,at 1000?,the type of product remained the same,the amount of production increased,there was a small amount of LNCM remaining in the reaction between LNCM and mullite,there was a small amount of LNCM and andalusite left in the reaction between LNCM and andalusite,in the reaction of LNCM and magnesium aluminum spinel,?-Li Al O₂ was converted into?-Li Al O₂,and there were remaining magnesium aluminum spinel and LNCM.LNCM reacted with zircon and forsterite at 750?,LNCM reacted with zircon to form Li₂Si O₃,LNCM reacted with forsterite to form Ni₂Si O₄,Co₃O₄,Li₂Co Si O₄,Li₂Si O₃ and Li Mn₂O₄;at 900?,LNCM reacted with zircon to form Li₂Si O₃,Co₂Si O₄,Ni₂Si O₄ and Li Mn₂O₄,Li₂Si O₃reacted with forsterite to form Li₂Si₂O₅,Li₂Si O₃ reacted with Mg O to form Li₂Mg Si O₄;at 1000?,the type of product remained the same,the amount of production increases and zirconite has completely reacted with LNCM.there was a small amount of forsterite remaining in the reaction between LNCM and forsterite,and the reaction of LNCM was complete.From the microstructure,the product grains that may be formed on mullite,andalusite,magnesium aluminum spinelzircon,zirconite and forsterite gradually grew with increasing temperature.?4?The physical and chemical reactions of LNCM precursor with cordierite and spodumene during the heating process were studied.LNCM reacted with cordierite and spodumene at 750?,LNCM reacted with cordierite to form Li Al Si O₄,Li Mn₂O₄,Co₃O₄,Mg Al₂O₄ and Ni₂Si O₄.LNCM reacted with spodumene to form Li Al Si O₄,Li Mn₂O₄,Ni₂Si O₄,Li₂Si O₃ and Co₃O₄;at 900?,the type of product remained the same,the amount of production increased.In the reaction of LNCM with cordierite,Co₃O₄ reacted with cordierite to form Co₂Si O₄,and the cordierite reacted completely.In the reaction between LNCM and spodumene,Li Al Si O₄ reacted with spodumene to form Li₂Al₂Si₃O₁₀,and reacted completely;At 1000?,the product development became more and more perfect.There was a small amount of LNCM remaining in the reaction between LNCM and cordierite,and part of the glass phase was produced.In the reaction between LNCM and spodumene,Co₃O₄ and Li₂Si O₃ reacted to form Li₂Co Si O₄,with spodumene had no remaining.In terms of microstructure,the product grains that formed on the surface of cordierite and spodumene gradually grew with temperature.?5?By studying the effect of raw material ratio,holding time and particle size on the reaction between LNCM precursor and refractory raw materials,different ratios of precursors react with alumina,mullite and cordierite to produce roughly the same products,as the ratio of the precursor to the refractory raw material gradually increased,from 1:2,1.2:1,to 2:1,from the perspective of microstructure,the product grains tended to grow gradually.The phase composition of the LNCM precursor and the refractory raw materials for 3h,6h and 9h is unchanged.Mg Al₂O₄ with a particle size of 44?m did not react with LNCM,the particle size of the magnesium aluminum spinel was reduced to 5?m,the two began to react,and?-Li Al O₂ was formed,and the grain size increased.