Dan Li,Ziye Kang,Hao Sun,Ying Wang,Haiming Xie,Jia Liu,Jiefang Zhu
Although redox mediator (RM) strategy can decrease the overpotential in Li-O 2 batteries by tuning the electrochemical formation/degradation of Li 2 O 2 from the circumscribed surface pathway to the solution one, the redox shuttling causes an unexpected RM degradation and a continuous deterioration of Li anode, finally leading to a poor cyclability. This work presents the first report detailing the development of a novel Mn x Co 3-x O 4 -decorated separator for Li-LiI-O 2 batteries. Benefiting from the promotion effect of Mn x Co 3-x O 4 nanocages on I − /I 3 − and I 3 − /I 2 redox coupling, the cell with as-prepared separator maintains a low charge potential of ~3.3 V till the death of cell cycling. In addition, as-prepared separator can efficiently restrain the redox shuttling, leading to an obvious improvement on cycling stability for the cell. Moreover, the contributions of LiI to the battery performance and the operation mechanism are systematically investigated. These results present a promising progress in the development of multi-functional separator materials for RM-involved Li-O 2 batteries and the new design of hybrid energy storage device.
Developing efficient catalysts for low reaction-temperature catalytic reduction of NO by CO (CO–DeNO x ) is desirable but very challenging. Here, we report that hierarchically interconnected porous (HIP) Mn x Co 3- x O 4 spinels, synthesized by a facile citric acid-assisted sol–gel method, can act as highly efficient catalysts for CO–DeNO x . The obtained Mn 0.3 Co 2.7 O 4 displayed a much-enhanced catalytic performance with 87% NO removal at 100 °C and a wide active-temperature window (100–400 °C). Its superior activity stems from the following reasons: (i) the high-valence of Mn 3+ , Mn 4+ , and Co 3+ species in the Co–O–Mn structure enables the high catalytic activity and the effective redox-cycling of the Co 3+ and Co 2+ adsorption sites; (ii) the HIP structure can significantly enhance gas diffusion. This work offers an avenue to design metal oxide catalysts for CO–DeNO x by effectively controlling the doping metal concentration and oxidation states of the active components.
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