Yiqiao Wang,Siyuan Pan,Huan Li,Dewang Li,Yong Guo,Sijia Chi,Chuannan Geng,Shichao Wu,Quan-Hong Yang
Despite lithium–air batteries having unprecedented theoretical energy supremacy, rambling Li2O2 growth typically impedes O2 diffusion and electron transfer, causing low capacity, poor charging kinetics and short cycle life. Herein, we propose synergistic catalysis in the cathode by engineering the crystal facet of Fe2O3 nanoplates and introducing a visible light-excited photochemical effect. The growth of Li2O2 is regulated with a uniform distribution, mitigating local product aggregation and thus reducing the barriers of O2 diffusion and electron transfer. The improved reaction kinetics lead to ∼420% capacity improvement, low charge potential, superior rate performance, and long-term stability (300 cycles) in actual air. We reveal a mechanism that photoelectrons around each catalyst node and the resultant homogeneous internal electric field increase charge transfer, decrease soluble intermediates, and enable high electrochemical reversibility of amorphous Li2O2 with an ordered process. This study provides inspiring insights for future research into controlling product ordering in Li–air batteries.
Lithium–sulfur batteries, as one of promising next-generation energy storage devices, hold great potential to meet the demands of electric vehicles and grids due to their high specific energy. However, the sluggish kinetics and the inevitable “shuttle effect” severely limit the practical application of this technology. Recently, design of composite cathode with effective catalysts has been reported as an essential way to overcome these issues. In this work, oxygen-deficient ferric oxide (Fe 2 O 3− x ), prepared by lithiothermic reduction, is used as a low-cost and effective cathodic catalyst. By introducing a small amount of Fe 2 O 3− x into the cathode, the battery can deliver a high capacity of 512 mAh g −1 over 500 cycles at 4 C, with a capacity fade rate of 0.049% per cycle. In addition, a self-supporting porous S@KB/Fe 2 O 3− x cathode with a high sulfur loading of 12.73 mg cm −2 is prepared by freeze-drying, which can achieve a high areal capacity of 12.24 mAh cm −2 at 0.05 C. Both the calculative and experimental results demonstrate that the Fe 2 O 3− x has a strong adsorption toward soluble polysulfides and can accelerate their subsequent conversion to insoluble products. As a result, this work provides a low-cost and effective catalyst candidate for the practical application of lithium–sulfur batteries.
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