Organic n-type electrodes are promising in sodium-ion batteries due to their high theoretical specific capacity,and properties that can be facilely tuned by structure modifications.However,the currently reported organ...Organic n-type electrodes are promising in sodium-ion batteries due to their high theoretical specific capacity,and properties that can be facilely tuned by structure modifications.However,the currently reported organic n-type electrodes encounter problems such as low voltage platform and poor cycling stability,and further investigation into structure-property relationships is urgently needed.Skeletal isomerization provides a good platform for investigating structure-property relationships of organic functional materials,and has been rarely studied for electrode materials.Herein,new n-type polymers based on dithiophenebenzo-4,5-dione are developed as cathode materials.PBD-1,with a carbonyl group at theα-position of the thiophene,exhibits a lower-lying LUMO level and more delocalized LUMO distribution than PBD-2,with a carbonyl group at theβ-position of the thiophene,which is conducive to Na+adsorption and electron transport during sodium storage.At a current density of 0.5C,the initial specific capacity of PBD-1 is 176 mAh g^(-1),with the capacity retention rate as high as 96.6%after 400 cycles.Notably,the PBD-1 electrode shows a high median voltage of 2.3 V.Moreover,a full cell is successfully assembled,revealing a stable discharge capacity of 105 mAh g^(-1)during 400 cycles(1 A g^(-1)),indicating potential practical applications.展开更多
基金supported by the Chongqing Graduate Research and Innovation Project(CYS240149)the Fundamental Research Funds for the Central Universities for support(SWU-XDJH202314).
文摘Organic n-type electrodes are promising in sodium-ion batteries due to their high theoretical specific capacity,and properties that can be facilely tuned by structure modifications.However,the currently reported organic n-type electrodes encounter problems such as low voltage platform and poor cycling stability,and further investigation into structure-property relationships is urgently needed.Skeletal isomerization provides a good platform for investigating structure-property relationships of organic functional materials,and has been rarely studied for electrode materials.Herein,new n-type polymers based on dithiophenebenzo-4,5-dione are developed as cathode materials.PBD-1,with a carbonyl group at theα-position of the thiophene,exhibits a lower-lying LUMO level and more delocalized LUMO distribution than PBD-2,with a carbonyl group at theβ-position of the thiophene,which is conducive to Na+adsorption and electron transport during sodium storage.At a current density of 0.5C,the initial specific capacity of PBD-1 is 176 mAh g^(-1),with the capacity retention rate as high as 96.6%after 400 cycles.Notably,the PBD-1 electrode shows a high median voltage of 2.3 V.Moreover,a full cell is successfully assembled,revealing a stable discharge capacity of 105 mAh g^(-1)during 400 cycles(1 A g^(-1)),indicating potential practical applications.
