Study On The Novel Two-dimensional Layered Compounds As Anode Materials For Potassium Ion Batteries

As a new type of alkali metal ion batteries,potassium ion batteries have been extensively studied and made great progress in recent years.Similar to traditional commercial lithium-ion batteries and the well-studied sodium-ion battery systems,potassium-ion batteries rely on the reversible intercalation and deintercalation process of alkali metal ions between the positive and negative electrodes during charge and discharge process to complete energy storage and conversion.Traditional lithium-ion batteries have the advantages of high energy density and reliable cycle characteristics,and have achieved great success in commercial fields such as consumer electronics,electric vehicles,and large-scale power grids,but with the rapid growth of consumption of lithium-ion battery components,the demand for lithium-ion batteries has increased greatly,which has also promoted the rapid increase in the cost of lithium-ion batteries and led to the development of newer energy storage systems such as sodium-ion batteries and potassium-ion batteries.Compared to lithium,sodium and potassium are abundant in the earth's crust and inexpensive.In addition,the standard redox potential of potassium in some non-aqueous electrolyte is lower than that of sodium or even lithium,which may lead to the higher voltage of potassium ion batteries,thereby enabling higher energy density.However,developing suitable electrode materials capable of reversibly storing relatively large-sized potassium ions remains a significant challenge.In this paper,the performance of novel two-dimensional layered compound nanomaterial Rhenium diselenide?ReSe₂?and Rhenium disulfide?ReS₂?used as the anode of potassium-ion batteries was studied in depth.ReSe₂ and ReS₂,which are transition metal sulfides,have the advantages of such as good electrical conductivity and high specific capacity and so on,but the continuous insertion and removal of potassium ions during charging and discharging will cause the collapse of the material structure and make both of them have poor cycle stability.By selecting the suitable potassium ion battery electrolyte and the rational combined with graphene,we have successfully improved the electrochemical potassium storage performance of ReSe ₂and ReS₂.Due to the good conductive substrate provided by graphene,the co nductivity of the ReSe₂@rGO and ReS₂@rGO composites is greatly improved.In addition,the presence of graphene can effectively fix ReSe₂ and ReS₂,so that the ReSe₂@rGO and ReS₂@rGO electrodes could maintain good structural stability in the process of cycling.In this way,both electrode systems exhibit higher specific capacity and excellent cycle stability as the anode of the potassium ion battery.