Hierarchical porous structured SiOx derived from diatomite as high performance anode for Li-ion batteries

Silicon-based anodes are the most promising candidates for advanced Li ion batteries (LIBs) with energy density over 400 Whkg −1 due to its high theoretical specific capacity. However, their scale applications are still restricted by the performance fading due to particle pulverization, electrode fracture as well as high production cost. Herein, we report a hierarchical porous structured SiO x (HP-SiO x ) prepared by a facile method of etching porous diatomite. It is primarily composed of crystalline silicon and amorphous silicon oxide. The optimized porous HP-SiO x demonstrates a hierarchical pore structure with 20-80 nm pores on the wall of macropores. The macropores could well accommodate the volume expansion during deeply lithiation, while the interconnected pores promote electrolyte permeation. Evaluated as anode in LIBs, it displays a discharge capacity of 668.5 mAhg −1 after 100 cycles, it gives a discharge capacity of 330mAh/g even at a higher current density of 500 mAhg −1 . The thickness of cycled HP-SiOx anode only expands by 60 % after 10 cycles, while other reported SiO anodes normally expand over 110 %. Moreover, the ionic conductivity of HP-SiO x anodes range from 7.24 × 10−9 cm 2 /s to 3.87 × 10−11 cm 2 /s. These improvement in electrochemical performance can be attributed to the fabrication of a hierarchical porous structure, which buffers the volume expansion during lithiation and facilitates ionic transportation within the electrode. The abundant resource of diatomite endows the large-scale, low-cost production of this hierarchical porous SiO x and underscore the potential for commercial applications in lithium-ion batteries.