Formation of Electrode Materials in the Process of Carbothermic Flux Smelting of Ilmenite Concentrate and Hydrothermal Refining of Titanium Slag

The present study demonstrates, for the first time, the fundamental possibility of producing electrode materials for sodium-ion batteries through low-temperature carbothermic smelting of ilmenite concentrate fluxed with calcined soda and diatomite, followed by aqueous refining of titanium slag. The primary phase composition of the slag includes Na2Ti3O7 (48.2%), Na0.23TiO2 (22.0%), Na2TiSiO5 (11%), and Na0.67Al0.1Mn0.9O2 (8.5%), which, upon hydrolysis, transform into a monophase titanium dioxide with intercalated sodium—Na0.23TiO2. Thermodynamic analysis of the heat effects of chemical reactions among raw materials and resulting products substantiates the role of silicon and sodium oxides, carbon, oxygen, and water in the formation of various electrode materials during carbothermic flux conversion and aqueous refining. Insights into the mechanisms of thermochemical formation and hydrothermal phase transformations offer a scientific basis for the development of intercalation systems from abundant and low-cost natural raw materials, bypassing the need for expensive precursor synthesis.