Carbon shell coated hollow NiCoSe_x composite as high-performance anode for lithium storage

Abstract

Hollow NiCoSe_x (H-NiCoSe_x) nanospheres encapsulated with carbon shell were prepared via one-step easy solvothermal method followed by the carbon coating process. H-NiCoSe_x@C has large interior void with the uniform dimension around 350 nm and the thickness of carbon shell around 20–30 nm. Coupling with the large interior void as well as robust protective carbon shell, H-NiCoSe_x@C can retain the reversible capacity of 805.6 mAh·g⁻¹ after 100 cycles at 200 mA·g⁻¹. In particular, H-NiCoSe_x@C delivers large reversible capacity of 1532.2 mAh·g⁻¹ upon cycling for 1000 loops at 1000 mA·g⁻¹ with the capacity retention as high as 128.2% upon long period of activation. Even at the high rate of 3000 mA·g⁻¹, its specific capacity still retains up to 659.3 mAh·g⁻¹. The superior lithium storage performances for H-NiCoSe_x@C profit from its robust hollow core-shell structure as well as enhanced electrical conductivity and ion transport.

摘要

通过一步简单的溶剂热及后续的碳包覆过程制备了碳壳封装的中空 NiCoSex (H-NiCoSex) 纳米球。H-NiCoSe_x@C 内部空隙较大并且平均尺寸大概 350 nm, 碳壳厚度约 20-30 nm 较大的内部空隙与坚固的保护碳壳相耦合, H-NiCoSe_x@C 在 200 mA g⁻¹ 循环 100 圈后, 仍然可保持 805.6 mAh·g⁻¹ 的可逆容量。尤其是经过长时间的活化, H-NiCoSe_x@C 在1000 mA·g⁻¹循环 1000 次后, 实现了 1532.2 mAh·g⁻¹ 的大可逆容量, 并且容量保持率高达 128.2% 即使在3000 mA·g^-1的高倍率下, 其比容量仍然保持在 659.3 mAh·g⁻¹。H-NiCoSe_x@C 优越的锂存储性能得益于其坚固的空心核壳结构以及增强的电导率和离子传输。

Graphic abstract