Constructing defect-rich CoO post smart Li extraction from spent Li-ion battery toward efficient oxygen evolution reaction

The recycling of spent LiCoO 2 batteries has attracted numerous attentions in view of their environmental and economic values. However, conventional hydrometallurgy strategies for spent LiCoO 2 recycling still undergo complicated processes that involve multiple steps, resulting in a high-value metal loss and a low value-added product. Herein, a facile method was developed to recycle lithium and repurpose oxygen vacancy-rich cobalt-based catalysts toward oxygen evolution reaction (OER). By roasting LiCoO 2 with ammonium sulfate salt at 975 °C for 120 min, lithium was converted into soluble Li 2 SO 4 and 99.2 % of Li could be preferentially leached by H 2 O, while cobalt was recycled in the form of highly pure cobalt oxide (M−CoO). Importantly, the M−CoO exhibited an excellent OER activity, superior to the spent LiCoO 2 , the prepared Co 3 O 4 , the commercial RuO 2 , and most of the reported cobalt-based catalysts. The results confirmed that the outstanding OER activity of M−CoO was originated from the rich surface oxygen vacancy, which facilitated the surface reconstruction to form a highly active layer of short-range order species during OER. This study showcased a novel approach to achieving a priority lithium recovery, coupled with an advanced route for catalyst regeneration, from spent lithium-ion batteries for energy conversion and storage devices.