Exploring titanium niobium oxides recovered from columbotantalite mineral as lithium-ion batteries electrodes

Abstract

Titanium niobium oxides (TNO) are chemically recovered from a mineral composed of cassiterite, columbotantalite, rutile and wollastonite. The process involves a series of steps, including pyrometallurgical processes, leaching, and liquid-liquid extraction. It takes advantage of the naturally occurring Ti in the extracted mineral, avoiding the separation of Ti and Nb to directly obtain the valuable Ti–Nb–O compounds. Two compositions can be obtained (Ti2Nb10O29 or TiNb2O7, named TNO-cal and TNO-black, respectively) depending on the thermal treatment after the chemical separation from the original mineral. These compounds have been characterized to describe their composition, morphology and crystallographic properties. The recovered material, without any further purification or functionalization, has been studied as anodes in Lithium-ion batteries (LIBs). Different electrochemical behavior has been observed for voltage ranges of 1–3 V and 0.01–3 V, being the second range which gives best results. In the 1–3V range, TNO-black exhibits a reversible capacity of up to 101.4 mA h g−1 at 1C and maintains 97 % capacity retention after 200 cycles, this is mainly due to Li + insertion/de-insertion processes. Additionally, when expanding the voltage range down to 0.01V, TNO-black displays a specific capacity of approximately 139.1 mA h g−1 after 200 cycles at 1C, whereas TNO-cal reaches a specific capacity of 169 mA h g−1. Extended cycling experiments at a 1C rate for both electrodes reveal that after 200 cycles samples deliver efficiencies relative to the maximum discharge capacity values of 83.4 % (TNO-cal) and 64.4 % (TNO-black), with mean coulombic efficiencies of 97.5 %. These results demonstrate that the recovered materials can effectively function as anodes for LIBs, offering promising application potential, despite the presence of residual silica from the mining process.