Lewis acid molten salt etching of MAX phases has emerged as a universal route to synthesize fluorinefree MXenes.However,the layer-stacked structure and halogen-rich termination of such MXenes limit their widespread us...Lewis acid molten salt etching of MAX phases has emerged as a universal route to synthesize fluorinefree MXenes.However,the layer-stacked structure and halogen-rich termination of such MXenes limit their widespread use in energy storage.Herein,a sequential ion intercalation strategy is proposed to modulate the interlayer structure of the molten salt-etched Ti_(3)C_(2)T_(x) MXene(MS-MXene)for improving its lithium storage performance.The sequential ion intercalation process involved immersing MS-MXene in mixed alkaline solutions of LiOH,NaOH,and KOH,allowing for the pre-intercalation of smaller Li^(+)ions,which then facilitated the subsequent intercalation of larger Na^(+)and K^(+)ions(Li/Na/K-MXene).Consequently,the interlayer spacing of MS-MXene experienced an expansion from 11.02Å to 11.22Å,endowing the Li/Na/K-MXene with abundant surface active sites and improved ion/electron transport capabilities.When configured as an anode for LIBs,the Li/Na/K-MXene exhibited a high capacity of 323.1 mA h g^(-1) at 50 mA g^(-1),a superior rate capability of 170.0 mA h g^(-1) at 2000 mA g^(-1),and robust cycling stability with no decay over 1200 cycles.The proposed approach shows promise for expanding to additional classes of MXenes and can potentially advance MS-MXene for practical energy storage applications.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.U2004212).
文摘Lewis acid molten salt etching of MAX phases has emerged as a universal route to synthesize fluorinefree MXenes.However,the layer-stacked structure and halogen-rich termination of such MXenes limit their widespread use in energy storage.Herein,a sequential ion intercalation strategy is proposed to modulate the interlayer structure of the molten salt-etched Ti_(3)C_(2)T_(x) MXene(MS-MXene)for improving its lithium storage performance.The sequential ion intercalation process involved immersing MS-MXene in mixed alkaline solutions of LiOH,NaOH,and KOH,allowing for the pre-intercalation of smaller Li^(+)ions,which then facilitated the subsequent intercalation of larger Na^(+)and K^(+)ions(Li/Na/K-MXene).Consequently,the interlayer spacing of MS-MXene experienced an expansion from 11.02Å to 11.22Å,endowing the Li/Na/K-MXene with abundant surface active sites and improved ion/electron transport capabilities.When configured as an anode for LIBs,the Li/Na/K-MXene exhibited a high capacity of 323.1 mA h g^(-1) at 50 mA g^(-1),a superior rate capability of 170.0 mA h g^(-1) at 2000 mA g^(-1),and robust cycling stability with no decay over 1200 cycles.The proposed approach shows promise for expanding to additional classes of MXenes and can potentially advance MS-MXene for practical energy storage applications.
