摘要
Spinel lithium titanate(Li_(4)Ti_(5)O_(12),LTO),with the merits of safety operation voltage,stable crystal structure,and minor lattice volume changes,becomes an optimal anode material for high-power Li-ion batteries.However,the inherent wide bandgap and low lithiation reactivity of Li_(4)Ti_(5)O_(12)bring about poor conductivity and lithiation dynamics,limiting its further applications.Herein,we design and prepare unique Li_(4)Ti_(5)O_(12)anode materials with extremely low dopant content of Na^(+)utilizing the amorphous precursors.The resultant Li_(4)Na_(0.008-)Ti_(5)O_(12.004)sample(denoted as NLTO-0.008)presents superior rate performances and cycle ability,with a reversible capacity of 149.4 mAh·g^(-1)at the current rate of10.0C.NLTO-0.008 retains the charge capacity of151.3 mAh·g^(-1)with a capacity loss of 0.5%after 1000cycles at the current rate of 1.0C(charge)/10.0C(discharge).The kinetic studies furtherly demonstrate that the lithiation reaction energy and diffusion energy barrier decrease by 28.8%and 30%,respectively.Crystal structure analysis indicates that Na^(+)occupies the 16d Li site and forms distorted LiO_(4)tetrahedron and TiO_(6)octahedron.This lattice distortion forms open diffusion channels,thus enhancing the Li^(+)diffusion dynamics and decreasing the lithiation reaction energy barrier for Li_(4)Ti_(5)O_(12).Therefore,the pre-sodiation strategy may arouse great interest in understanding and developing intercalation-type transitionmetal-based electrode materials in high-power lithium-ion batteries.
基金
financially supported by the National Natural Science Foundation of China(No.52002116)
the Key Science and Technology Program of Henan Province(No.192102210004)。
