High-power recycling: upcycling to the next generation of high-power anodes for Li-ion battery applications

Abstract

With the growing interest in niobium-based anodes for high-power lithium-ion batteries (LIBs), current chemistries (for this application) such as Li₄Ti₅O₁₂ (LTO) anodes will be superseded, and as such an efficient and effective method of recycling needs to be considered. With this motivation, a potential upcycling route is proposed for LTO for the first time, such that Li is recovered as a salt and the titanium oxide (anatase) repurposed and used in the synthesis of current generation titanium-doped niobates. Using a variety of inorganic acids: HCl, H₂SO₄ and H₃PO₄ to achieve the proton-lithium exchange, the lithium was found to be completely leached from the LTO in the former 2 acids. The latter acid was found to give incomplete leaching, with the formation of LiTiOPO₄. In addition to the recovery of Li from the leached solution, we also investigated upcycling of the recovered TiO₂ (anatase) into next generation anodes TiNb₂O₇ and Ti₂Nb₁₀O₂₉. The rate performance of these upcycled materials was determined through the fabrication of Li half coin cells, where both materials were found to show excellent performance at high rates (219 (2) mA h g⁻¹ and 168 (16) mA h g⁻¹ at 2 A g⁻¹ for TiNb₂O₇ and Ti₂Nb₁₀O₂₉ respectively), highlighting the potential of this recycling strategy for LTO.