Towards higher quality directly recycled TiNb2O7: elimination of lithiated rutile impurity phase

With the growing demand for sustainable lithium-ion battery (LIB) technologies, the development of efficient recycling processes for electrode materials is critical. TiNb2O7 (TNO) is gaining increasing attention as a promising anode material for high power Li ion batteries due to its high rate capability, excellent structural stability, and safer operating voltage compared to conventional graphite. However, recycling strategies for TNO remain underdeveloped. This study presents a direct recycling approach for TNO anodes recovered from a cycled TiNb2O7/ LiNi0.6Mn0.2Co0.2O2 (TNO/NMC622) cell. A full range of procedural steps including electrochemical cycling of the TNO/NMC622 pouch cell, cell dismantling, electrode delamination, materials recovery and repair, and lastly cell remanufacturing and electrochemical evaluation were investigated. The results showed that residual lithium in the TNO can lead to a rutile-type impurity, which is detrimental to performance. To address this, a recycling approach was developed, combining hydrothermal lithium removal with a post heat treatment. Electrochemical testing of the recovered TNO highlighted that lithium removal is crucial as the recovered material without Li removal showed poor performance, while recycled TNO after Li removal exhibited high capacity and excellent rate capability and stability at high current densities, 279(5) and 261(10) mA h g-1 at 2 and 4 A g-1 respectively, similar to top-of-the-range commercial TNO.