Co(acac)<sub>2</sub>-Mediated Regulation of Li<sub>2</sub>O<sub>2</sub> Gradient Growth in Lithium–Oxygen Batteries
Xingzi Zheng, Peiyuan Su, Jingshen Xu, Qingyu Kong, Jianing Yue, Wenli Su, Jihao Zhang, Siao Li, Wei Xiong, Xingyu Chen, Feifei Su, Qiangqiang Zhong, Jiachang Huang, Haomin Jiang, Mengwei Yuan, Wenkai Zhang
Abstract
In Li–O 2 batteries, Li 2 O 2 serves as the primary cathodic material but its wide band gap imparts insulating properties. Regulating the composition and morphology of Li 2 O 2 enables the construction of a novel cathodic structure with exceptional electrochemical performance. Herein, we introduce an organic salt containing cobalt ions, cobalt acetylacetonate (Co(acac) 2 ), into the cathodic electrolyte. We exploit its cation migration characteristics under an electric field to facilitate the generation and decomposition of Co-doped Li 2 O 2, achieving gradient control and optimized growth of Li 2 O 2 . Moreover, the Co(acac) 2 molecule stabilizes the properties of LiO x species and mitigates side reaction. In situ UV–vis and XANES spectra reveal direct interactions between Co(acac) 2 and O 2 – /LiO 2, highlighting the superior reversibility of Co(acac) 2 enhanced Li–O 2 batteries. Both experimental and theoretical results indicate that this novel Li–O 2 battery system exhibits rapid reaction kinetics, with a reduced overpotential of 520 mV and extended cyclability, surpassing 400 cycles with lower polarization.