Superior corrosion resistance KAlSi2O6-containing materials for calcining Li-ion battery cathode materials

Synthesized K2O·11Al2O3 as sagger matrix for the preparation of Li‐ion battery cathode materials at high temperatures

“…These observations illustrate that the consumption of corundum (Al 2 O 3 , "A" in Figure 2) is attributed to the interactions to form lithium aluminum oxide (LiAlO 2 , "γ" in Figure 2) and nickel aluminum oxide (NiAl 2 O 4 , λ in Figure 2). Furthermore, the peaks of potassium aluminate KA 11 ) phases formed from the interactions during 800-1100°C between KA 11 and LNCM precursors are remarkably less than mullite, cordierite, forsterite, andalusite, and even corundum, [5][6][7][8] further confirming that KA 11 -based material has a better corrosion resistance to LNCM materials compared with mullite, cordierite, forsterite, and andalusite.…”

“…These observations suggest that the extent of reaction between KA 11 and LNCM cathode material is less, comparing with mullite, cordierite, forsterite, and andalusite. [5][6][7][8] However, after calcining at 1100°C (Figure 3D), a layer consisting of light gray-appearing phases (Point 2 in Figure 3D) can be observed around KA 11 grains with a smaller particle size. EDS spot measurements (Figure 3E and Table 3) suggest that the light gray-appearing phases should be NiAl 2 O 4 spinel-based solid solution, indicating that interactions occur between LNCM precursors and KA 11 materials at higher calcination temperatures, and the reaction products, for example, NiAl 2 O 4 spinel-based solid solution precipitate around the KA 11 grains boundary.…”

“…The observations show that little interaction between KA 11 and LNCM material occurs during the calcination at 800-900°C, whereas the interaction happens in limited extents at 1000°C and 1100°C, compared with mullite, andalusite, cordierite, and forsterite. [5][6][7][8] Figure 4 shows the diameter expansion rate of mullite-LNCM precursor, corundum-LNCM precursor and KA 11 -LNCM precursor cylinders after calcination at 800-1100°C for 6 h. The KA 11 -LNCM sample presents the expansion trend with the temperature increase and the different expansion rates should be caused by the different extent of reactions between KA 11 and LNCM precursors inside the cylinder samples. The diameter change rate of the KA 11 containing sample is below 2% when the calcination temperature is 800°C and 900°C, whereas the expansion rate of the KA 11 containing sample is 2.6% when the temperature is 1000°C, and the rate increases significantly to 3.4% after calcining at 1100°C.…”

“…To ensure the calcination proceeds consecutively at high temperatures, the LNCM precursors were normally loaded in refractory saggers prepared with corundum (Al 2 O 3 ), mullite (3Al 2 O 3 ·2SiO 2 ), andalusite (Al 2 O 3 ·SiO 2 ), forsterite (2MgO·SiO 2 ), cordierite (2MgO·2Al 2 O 3 ·5SiO 2 ), etc 4,5 . However, it has been reported in previous work via post‐mortem analyses and laboratory‐scale tests that the conventional refractory components in refractory sagger matrix can be severely corroded by LNCM materials at elevated temperatures 5–8 . These refractory compounds are preferentially attacked by Li 2 O from LNCM materials/precursors, forming Li 2 O‐bearing phases, that is, LiAlSiO 4 , LiAlSi 2 O 6 , and LiAlO 2 with volume expansions.…”

“…To ensure the calcination proceeds consecutively at high temperatures, the LNCM precursors were normally loaded in refractory saggers prepared with corundum (Al 2 O 3 ),However, it has been reported in previous work via post-mortem analyses and laboratory-scale tests that the conventional refractory components in refractory sagger matrix can be severely corroded by LNCM materials at elevated temperatures. [5][6][7][8] These refractory compounds are preferentially attacked by Li 2 O from LNCM materials/precursors, forming Li 2 O-bearing phases, that is, LiAlSiO 4 , LiAlSi 2 O 6 , and LiAlO 2 with volume expansions. As a result, parallel cracks along the refractory/LCNM materials interfaces were generated, leading to the spalling of corroded refractory materials…”