Rational Design And Catalytic Performance Investigation Of Ag₂Te And Pd@Te For The Flexible Cathode Of Lithium-Oxygen Battery

In order to address the increasingly serious energy shortage and environmental pollution issues,worldwide research on sustainable and clean energy has become increasingly important.Currently,among various advanced energy storage systems,lithium-oxygen batteries are considered an excellent candidate for the next generation of energy storage devices due to the ultra-high theoretical energy density(3505 Wh kg^-1)which is close to gasoline.Meanwhile,it exhibits the characteristics of simple structure,high safety,and low cost.However,the research on lithium-oxygen batteries is still in its initial stage,and the problems of low actual capacity,poor cycle stability,and high overpotential have been hindering the application of lithium oxygen batteries.The non-conductive discharge product（Li2O2）has always been one of the biggest reasons why it is difficult for lithium oxygen batteries to fully achieve excellent performance.The buildup of LiO2 during charging and discharging process reduces the conductivity of the cathode and leads to slow reaction kinetics,while strong oxidation intermediates react with the battery components to form by-products,resulting in a dramatic degradation of the battery performance.Therefore,the development of cathode catalysts that can effectively promote the formation and decomposition of lithium peroxide,reduce the occurrence of side reactions during the reaction process,and have long-term cycle stability has become a key way to achieve a leap in the performance of lithium oxygen batteries.Meanwhile,due to the rapid development of flexible electronic devices,the demand for flexible energy storage devices has also increased.A large number of studies have begun to focus on the flexibility of lithium oxygen batteries and their application to flexible electronic equipment,wearable devices,and so on.Current research on cathode catalysts for lithium oxygen batteries is mainly limited to loading catalysts onto rigid substrates such as carbon paper,which greatly limits the flexible application of lithium oxygen batteries.In this work,based on the design and synthesis of high-performance catalysts with nanowire morphology,a flexible self-supporting cathode was prepared.The characteristics of its materials and its reaction characteristics with discharge products during the reaction process were systematically studied.Ag₂Te nanowires and Pd@Te nanowires were used to prepare flexible cathode for lithium oxygen point batteries by vacuum filtration.The catalytic characteristics and reaction mechanism of the materials were studied through experimental means and theoretical calculations.The main research content of this article is as follows:（1）Firstly,Ag₂Te.a narrow band gap telluride with a binary stacked structure,has been used as a flexible cathode catalyst in lithium oxygen batteries,and has achieved excellent electrochemical performance,which was able to cycle 160 cycles at a fixed capacity of 0.1 mAh cm^-2 and to reach a capacity of more than 6 mAh cm^-2 in the first charge/discharge test.Meanwhile,a flexible lithium oxygen battery with Ag₂Te nano wires as a flexible cathode was assembled.Through experiments and theoretical calculations,the different structures and electronic states of the two-dimensional stack surface and side surfaces were studied,and the different catalytic characteristics for the adsorption of different discharge products were studied.The work in this paper predicts the highly active catalytic ability of tellurides,and studies the catalytic anisotropy derived from the layer structure of Ag₂Te.This may be helpful to understand the mechanism of two-dimensional materials containing van der Waals forces in the catalytic process,and lay a foundation for the application of metal tellurides in advanced energy devices.（2）Te nanowires,which is suitable for preparing flexible electrodes,were synthesized as a substrate,and in order to improve their performance in lithium oxygen batteries,amorphous Pd clusters with uniform distribution were loaded on their surfaces.The morphology and structure of the Pd@Te nanowires were analyzed by comprehensive testing methods.Pd@Te2（Pd:Te=1:10）flexible cathode nanowires exhibit the best electrochemical performance,which was able to cycle 190 cycles at a fixed capacity of 0.1 mAh cm^-2 and to reach a capacity of more than 3.35 mAh cm^-2 in the first discharge test.Theoretical calculations show that the uniform electron distribution and excellent electrical conductivity of Pd surface enable uniform adsorption/desorption of discharge products during the catalytic process,while the high adsorption energy of Te surface for Li species allows it to supplement the weak adsorption of Pd surface to Li species during the catalytic process,and the difference in control steps can maintain the smooth progress of intermediate conversion during the catalytic process.Pd@Te The preparation of nano wire flexible electrodes provides an effective reference for how to form composite catalysts with noble metals and non-metallic materials such as Te to improve the synergistic catalytic ability.