Developing high-capacity and high-rate anodes is significant to engineering sodium-ion batteries with high energy density and high power density.Layered Na_(2)Ti_(3)O_(7)(NTO),with an open crystal structure,large theo...Developing high-capacity and high-rate anodes is significant to engineering sodium-ion batteries with high energy density and high power density.Layered Na_(2)Ti_(3)O_(7)(NTO),with an open crystal structure,large theoretical capacity,and low working potential,is recognized as one of the prospective anodes for sodium storage.Nevertheless,it suffers from sluggish sodiation kinetics and low(micro)structure stability triggered by a high Na+diffusion barrier and weak adhesion of[Ti_(3)O_(7)]slabs.Herein,the interlayered local structure of NTO is regulated to solve the above issues,in which parts of interlayered Na^(+) sites are substituted by H^(+)(Na_(2−x)H_(x)Ti_(3)O_(7)[NHTO]).Theoretical calculations prove that the NHTO offers lower activation energy for Na^(+)transports and low interlayer spacings with alleviated Na-Na repulsion and relatively flexible[Ti_(3)O_(7)]slabs to reduce fractural stress.In situ and ex situ characterizations of(micro)structure evolution reveal that NHTO goes through transformation between H-rich and Na-rich phases,resulting in high structure stability and microstructure integrity.The optimal NHTO anode delivers a high capacity of 190.6 mA h g^(−1) at 0.5 C after 300 cycles and a superior high-rate stability of 90.6 mA h g^(−1) at 50 C over 10,000 cycles at room temperature.Besides,it offers a capacity of 50.3 mA h g^(−1) after 1800 cycles at a low temperature of−20℃ and 195.7 mA h g^(−1) after 500 cycles at a high temperature of 40℃ at 0.5 C.The developed topologically interlayered local structure regulation strategy would raise the prospect of designing high-performance layered anodes.展开更多
基金National Natural Science Foundation of China(Grant No.52202282)Opening Project of the State Key Laboratory of High-Performance Ceramics and Superfine Microstructure(Grant No.SKL202209SIC)Natural Science Foundation of Tianjin City(Grant No.22JCYBJC00040).
文摘Developing high-capacity and high-rate anodes is significant to engineering sodium-ion batteries with high energy density and high power density.Layered Na_(2)Ti_(3)O_(7)(NTO),with an open crystal structure,large theoretical capacity,and low working potential,is recognized as one of the prospective anodes for sodium storage.Nevertheless,it suffers from sluggish sodiation kinetics and low(micro)structure stability triggered by a high Na+diffusion barrier and weak adhesion of[Ti_(3)O_(7)]slabs.Herein,the interlayered local structure of NTO is regulated to solve the above issues,in which parts of interlayered Na^(+) sites are substituted by H^(+)(Na_(2−x)H_(x)Ti_(3)O_(7)[NHTO]).Theoretical calculations prove that the NHTO offers lower activation energy for Na^(+)transports and low interlayer spacings with alleviated Na-Na repulsion and relatively flexible[Ti_(3)O_(7)]slabs to reduce fractural stress.In situ and ex situ characterizations of(micro)structure evolution reveal that NHTO goes through transformation between H-rich and Na-rich phases,resulting in high structure stability and microstructure integrity.The optimal NHTO anode delivers a high capacity of 190.6 mA h g^(−1) at 0.5 C after 300 cycles and a superior high-rate stability of 90.6 mA h g^(−1) at 50 C over 10,000 cycles at room temperature.Besides,it offers a capacity of 50.3 mA h g^(−1) after 1800 cycles at a low temperature of−20℃ and 195.7 mA h g^(−1) after 500 cycles at a high temperature of 40℃ at 0.5 C.The developed topologically interlayered local structure regulation strategy would raise the prospect of designing high-performance layered anodes.
