Damage Mechanism And Optimization Of Saggar For Sintering Li-ion Battery Cathode Materials

At present,under the background of green and low-carbon economy,Li-ion batteries have shown great application potential and market due to advantages such as high energy,wide working temperature range,long storage life and low pollution.As an important part of Li-ion batteries,the production efficiency,quality and economic benefits of cathode materials are facing more stringent challenges.The development of saggar for sintering cathode materials with low production cost and excellent comprehensive performance is an important problem to be solved urgently.The performance of saggar mainly depends on the composition,structure and production process of raw materials,and its service life is affected by specific service environments such as temperature,atmosphere and corrosion.Based on this,it is necessary to analyze the damage mechanism of the saggar and try to effectively optimize the design.The relevant research conclusions are as follows:（1）The phase composition and microstructure of the post-service saggar（mullite（3Al₂O₃·2Si O₂）-cordierite（2Mg O·2Al₂O₃·5Si O₂）as the substrate,corundum（Al₂O₃）-spinel（Mg O·Al₂O₃）-zircon（Zr O₂·Si O₂）as the composite layer）were systematically characterized and analyzed.In addition,the thermodynamic calculation of the interface reaction between the saggar and the cathode material was carried out by using Factsage 6.2 software,and the corrosion test of Li Ni_0.8Co_0.1Mn_0.1O₂（LNCM）was carried out.To clarify the corrosion and damage mechanism of the saggar.（2）In order to improve the service performance of the saggar by in-situ formation of anorthite（Ca O·Al₂O₃·2Si O₂）,ferrotitanium slag was selected as an additive to add to the mullite–cordierite saggar.It was found that the addition of CAT helped to promote the sintering of the saggar and increase its bulk density and mechanical strength（especially high temperature mechanical properties.At 1100°C,the hot modulus of rupture of 0 wt%CAT sample is 15.06 MPa,but the hot modulus of rupture of 9 wt%CAT sample is 22.75 MPa）.The sintering mechanism of saggars containing CAT was analyzed by thermodynamic simulation of Factsage.In addition,static crucible corrosion experiments have been performed to investigate the effect of CAT on the corrosion resistance of saggars.It has been shown that CAT-containing saggars have excellent corrosion resistance.（3）Attempting to use PMM to replace mullite particles as the main aggregate of the saggar to achieve the lightweight of the saggar to reduce consumption and improve efficiency.It is found that the pores on the surface of PMM are beneficial to the entry of fine powder,which makes PMM more closely combined with the matrix and helps to improve the sintering performance of the saggar.The porous structure of PMM provides a buffer space for the thermal expansion of mullite,which is beneficial to alleviate the adverse effects of volume expansion and thermal stress improve of the saggar at high temperatures.