Design of experiment using double perovskite to inhibit shuttle effects in lithium-sulfur batteries
[Objective]As global demand for renewable energy grows,the development of sustainable energy storage devices with high energy density becomes increasingly crucial.Owing to their high energy density and cost-effectiveness,lithium-sulfur(Li-S)batteries have been regarded as the most promising next-generation energy storage systems.However,several challenges hinder their practical applications,notably the shuttle effects of soluble lithium polysulfides(LiPSs).This issue leads to rapid capacity decay and a short cycling lifespan,severely limiting the development of Li-S batteries.Thus,it is imperative to discover and design various novel materials for use in Li-S batteries to inhibiting the shuttle effects of LiPSs and explore the underlying mechanism.In the context of"Emerging Engineering Education,"cultivating students'innovative thinking and problem-solving abilities is also highly important.However,the current experimental teaching rarely emphasizes Li-S batteries and the key issue of LiPSs'shuttle effects.Therefore,a comprehensive research experiment on the shuttle effects of Li-S batteries has been designed to deepen students'understanding of the working principles and challenges of these types of batteries.This experiment aims to suppress the shuttle effects of LiPSs in Li-S batteries using a typical double perovskite as an inhibitor.[Methods]Specifically,a double perovskite oxide La2CoMnO6 is synthesized via a simple sol-gel method.Then,a static visual adsorption experiment of La2CoMnO6 to Li2S6,as well as a catalytic experiment using La2CoMnO6 as a catalyst,are designed to investigate the chemical absorption and catalytic efficiency of La2CoMnO6 to LiPSs and analyze the inhibition effect of La2CoMnO6 on the shuttle effects of LiPSs.Finally,a suitable amount of La2CoMnO6 powder was applied as a cathode additive to explore the influence of La2CoMnO6 inhibitors on the electrochemical performance and cycling lifespan of Li-S batteries.[Results]The experimental results are summarized as follows:1)The Li2S6 solution containing La2CoMnO6 adsorbent has a lighter color and lower UV-Vis spectra absorption intensity compared to the solution containing carbon nanotubes(CNTs).This indicates that La2CoMnO6 has a stronger chemical absorption to Li2S6 than CNTs.Moreover,the appearance of an obvious S-Co bond peak in X-ray photoelectron spectroscopy of La2CoMnO6 after absorbing Li2S6 further confirms the strong chemical interaction between Li2S6 and La2CoMnO6.2)The response current of La2CoMnO6-based symmetric batteries with Li2S6 solution as electrolyte obviously increases,indicative of the enhanced catalytic performance of La2CoMnO6 to Li2S6,promoting conversion kinetics of Li2S6 and thus inhibiting its shuttle effects.3)Li-S batteries with La2CoMnO6 inhibitor exhibit increased reduction peak potential and current densities in CV curves and decreased charge transfer resistance.These findings suggest that adding La2CoMnO6 improves the electrochemical conversion process of LiPSs.4)Li-S batteries with La2CoMnO6 inhibitor yield a significant increase in discharging specific capacity at different rates.They also exhibit better rate performance and cycling lifespan compared with Li-S batteries without La2CoMnO6 inhibitor.[Conclusions]In conclusion,La2CoMnO6 can efficiently suppress the shuttle effects of LiPSs owing to its strong chemical absorption and catalytic action on LiPSs.This contributes to improved electrochemical performance and cycling lifespan of Li-S batteries.Overall,this experiment is beneficial for stirring students'innovative spirit and research interest.Moreover,it cultivates students'ability to conduct scientific research and resolve practical problems by fully utilizing theoretical knowledge.
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